Sending the girls home was the right thing to do. If you can, don't engage her when this happens. Drop back from Basket B to Basket C, in other words.
This is not easy and it is going to take time. I wish I had more to reassure you with. And you are right to be anxious about Christmas - she will be away from her comfort zone, she will be surrounded by stimulation and distraction.
About bedtime - while a routine is a good thing, if there are battles over it, especially when the routine is disrupted, you might need to relax things. But if you already have a routine that works, you can TRY and adapt it.
Does she read at all? For difficult child 3, reading is important. It's also been important for difficult child 1, in his routine as he was growing up. Within the autism label they each have different dysfunctions. difficult child 1 has great difficulty multitasking, especially if it involves trying to remember a series of tasks or a sequence of steps. So we wrote it down for him on a small blackboard we have. The blackboard is not a discipline thing, it's an aid. So for example, we would get difficult child 1 to pack his own things for a trip, by writing out the list. If she is not reading, then draw pictures beside the words, but do use the written words too so there is a connectedness for her. And maybe suggest she collect her things while you are doing yours - that way she is doing a grownup thing. If she won't, then skip it. Pack her things later. But giving her a list may make it easier for her to pack the right things and not get too upset when you don't take absolutely everything of hers.
Choices work better than ultimatums. Also, if it is possible to talk to hr when she's calm, about what she would like to do to try to calm down next time she is upset - it might help. I don't know if she has the maturity for this yet. We used to send the boys to their room (not at the same time). They learned that being sent to their room was not a punishment, it was a cooling off space. But difficult child 3 was never as good with this as the other kids, who would sometimes storm off mid-tantrum and put themselves in their rooms!
difficult child 1 would go climb a tree when he was upset. Or I would send him outside to cool off. Putting them in a bath also worked, especially for easy child 2/difficult child 2 and difficult child 2, because water has always calmed them. difficult child 3 also calms down when given a small bubble blower (like those $1 ones sold in discount shops, or the ones they hand out at weddings). I used to collect these and top them up with slightly watered down dishwashing liquid. We also got a bucket with a large bubble wand (the ones sold for about $5 at school fetes, etc). We kept the bucket full of bubble mix - mostly water with about quarter cup of dishwashing liquid, mixed together gently. It takes about fifteen minutes to mix it properly, the first bubbles will be too weak. But don't be tempted to add more detergent until the bubbles are consistently still weak after 10-15 minutes. You should see them get stronger - once they are constant and still weak, add more. A teaspoon of glycerine makes the bubbles last longer.
We used to send difficult child 3 outside to make bubbles - you wave the wand around gently and the wind does the rest.
If you can't afford/don't have a bubble wand, make one out of a wire coathanger, just bend it into a circle. Not as good, but it still works.
At this early stage, you're in Aim No 1 - keep her calm, or defuse a rage. If having the neighbour girls visit is triggering a meltdown (and it does seem to be a link) then keep their visits either shorter, or restrict them entirely. Sending them home while things are still nice is the aim, because their visits will then be entirely positive. Or maybe limit the visit to one at a time, not on the same day.
At home, with you, in her routine (and whether you realise it or not, she does have one) can be the stable starting point.
This is a horrible time of year anyway; it's even worse to try and introduce something new. It will make it slower, and over Christmas with other relatives each putting in their oar could make you feel even less confident in your abilities. Be forewarned.
When you get to where you are staying, maybe the first thing to do is help her set up her refuge. She needs to be introduced to a place where she can go to be alone and try to get away from whatever is upsetting her (and things will upset her). Call it her "safe place" or whatever you think she will accept. "Personal space" maybe, because then you can justify having your own "personal space" she is not permitted to invade while raging. Whenever we're away, we try to make difficult child 3's "personal space" the place where he will be sleeping. This isn't always possible if you will be sleeping in a motel, say, but spending the days at someone's home. You need a space in any place you are spending time, so a personal space in the motel as well as in the person's home is going to be needed.
One personal space option can be the toilet, if it's not part of the bathroom, or the only one. The back porch; the front porch; the back fence; an empty bedroom. Make sure there is nothing she is likely to damage, and something she can cuddle or scream into. difficult child 3's fetish for towels - we would make sure there was a towel there that he could hold.
Sometimes we made our car the 'safe place', as long as it wasn't parked in the sun, of course!
As things are at the moment, she is attacking you when upset and not going off alone. This is a big worry, as well as emotionally and physically exhausting for you. Maybe your first Basket B item can be teaching her to use a 'personal space'?
Reward is good. The trouble is, I can hear you say - first she's got to do something good to justify reward! But rewards can be tiny, and given purely for the brief moments of silence between screaming breaths, if necessary. (well, maybe that's a bit extreme).
If I'm having a bad day with difficult child 3 (and we sure do have 'em, especially if he's been repeatedly aggravated by people or circumstances beyond our control) then as far as possible, I ignore and don't engage. I use hand signals - a hand held up plus the word "Stop!" or "Enough!" although this took time and a lot of patience to learn. He also needed to know that I would let him say what he wanted to say - he can't be interrupted or hurried, it triggers a rage (triggers rage in easy child 2/difficult child 2, as well, and she's an adult - technically).
difficult child 3's bad day - I wait for the first opportunity to say, "Thank you," to him. It might be, "Thank you for waiting for me," or "Thank you for listening," or "Thank you for sitting quietly for a few minutes, it gave me time to think about what we will have for lunch."
Even if I get a grumpy response along the lines of, "I wasn't meaning to be good; if I'd realised I was doing something you were happy with, I'd have been mean just to make you unhappy," I still say calmly, "It doesn't matter to me why. I'm still saying thank you. I appreciated it, even if it was by accident."
You need to look for opportunities to catch her out being good (or not being horrible) and praise her for them. Don't overdo it - she will recognise insincerity and resent it. You need to become a method actress and for the moment you say it, really mean it.
It is amazing how this can snowball. It starts off with you wracking your brain, trying to find something, anything, to praise her for. Then you learn what to look for at about the same time she realises she likes your approval far more than she values the outcomes of her tantrums.
A tantrum can get you what you want. It can have a positive payoff. But it has a down-side - you wear yourself out, you have a lot of adrenalin zinging through your body and making you feel hot, bothered and anxious, and the post-tantrum let-down is depression. Sometimes quite a deep depression, even if it's only for half an hour or so. What you are trying to balance here, is the outcome of her getting her own way as the result of a tantrum, and the outcome of her feeling a bit better about herself because you found something to praise her for.
She needs to be calm enough after a successful praise encounter, to be able to work out for herself what is happening and how she feels. Again, this takes time and opportunity. And you can't force anything. You just have to, for a while, let her set the pace. For a little while at least, allow her to make her own choices as far as you can, as long as she is safe and isn't destroying things. And as she is doing this, watch her and try to get inside her head. If you're looking for an opportunity to praise, watching her and thinking will be easier anyway.
Sorry to be so pessimistic, but I don't want you to take things personally over Christmas if things are rough. And if things go better than expected - great!
Basically, aim for lots of brief, small, successes rather than one long disaster triggering another. Short encounters, lots of down-time (for both of you if possible) and plenty of rest for both of you is the prescription. Try to avoid controlling her unless absolutely necessary for her immediate safety or something else equally important. Make sure you both get plenty of sleep and don't let her get too hungry or thirsty - she will be more pliable when rested and fed.
After Christmas, something to consider - sometimes certain foods, additives etc can trigger worsening behaviour. Don't worry about it now, but if you think you observe something over the next few days/weeks as you are making your notes on her, then jot that down too. It could be useful information later on.
For example, we know that caffeine makes both my boys a lot worse, especially difficult child 3. easy child 2/difficult child 2 was also affected but seems to have grown out of it. difficult child 1 still has a trace of a problem if he has too much caffeine. When we restricted caffeine, difficult child 3's behaviour improved a lot.
We did consider diet also with difficult child 3. For about 30% of kids on the spectrum, modifying the diet according to careful guidelines can bring about an improvement in a number of areas. Apart from caffeine, there was no benefit for difficult child 3 when we tried it. For more info, check out the Allergy Clinic at RPAH. Ann Swain and Rob Loblay.
You are going to have bad days. It happens to all of us. Don't feel you're a failure, from what you've told us so far I think you've got good instincts and are doing well, considering. This isn't so much about success/failure, as about trying to find the right key. You daughter is the locked door, you're standing at the door with a bunch of keys trying to find which one fits the lock. The door slams shut from the wind even after you open it, it's just a matter of practice and experience to help you learn which is the right key, and how to find it faster each time.
You're not a failure at all. Just busy. Tired. Challenged. Like all of us.
It does get better from here, especially after Christmas. Maybe even before?
Marg