Another very powerful tool is the Parent Report. I found it to be incredibly powerful, especially as treatment got more complicated with medication and doctors. What is it? A report that you write that tells everything about your child - and I mean EVERYTHING! Parents here long before me came up with it and it is really complete. I did find having a photo at the beginning of every section to be helpful (I used the same photo so that I didn't confuse the doctors). It reminded the doctors who they were reading about. You can get to the thread with the outline for the Parent Report from the link in my signature at the bottom of this post.
The report is especially useful when you use medications. You can keep medications and side effects at your fingertips. Often you remember them better than the doctors, but just telling a doctor often doesn't carry as much weight as having it in black and white. Why? Who the heck knows. I had a few docs who would get quite upset with me when I would refuse to "try" a medication on my son when I knew it had given him bad side effects in the past. It gave me a reputation of being uncooperative, which I found to be ludicrous. If I had given him a medication that I knew made him very ill (one gave him breathing problems!!!), they probably would have reported me to CPS and investigated me. Being able to show the doctor a paper with the name of the medication and the side effects written down somehow made the side effects legitimate for some doctors, as if I couldn't have made them up, as if I wasn't the one who typed the paper! (This was before tablets.) It just made things so much easier to have it all written down.
I even gave the doctors copies of sections that were relevant to the things they were treating my son for. I always had a copy or 2 of the report with me at reports and IEPS and things. I found that it looked intimidating at the IEPs, if nothing else. Heck, it was often me against 10 or more people at those things, I would do whatever I could, LOL!
The report really did make a HUGE difference. Now you could even include video if you wanted to. Especially if you could take it without your child noticing. That can be super helpful to a doctor making a diagnosis. Sometimes seeing a mood change can be HUGE, or seeing the difference in behavior after a mood changes. Just a thought.
Medication is really a personal thing. I will say that without medication, my son would never have been able to cope. He is still on his medications, by choice. He says he likes himself on his medications. He has unipolar depression, which is incredibly rare. His psychiatrist says he only has a handful of patients with this diagnosis, because most patients go into at least a mixed state. His doctor, who I have never met, interviewed my parents and Wiz and read the Parent Report carefully before continuing Wiz' medications. Wiz was living with my parents by that point, and Wiz didn't think I needed to meet his doctor. He was stable and almost 18 by then, and I was fine with it. He had never gone manic and had been on many antidepressants before. It took a combination of 3 of them to really pull him into functionality. Yes, 3 antidepressants. One treats ADHD. One is for sleep. One is for depression. The 2 not for depression also work on his depression. They are just also effective on other things. It is very hard to find the right medications.
Has the doctor told you that the SSRI/SNRI antidepressants can trigger mania and other very serious side effects in children? To the point that there is a Black Box warning on the box, issued by the FDA? Not every child gets these. My son did not. My daughter led her class in a conga line when the teacher told them to sit down to do a lesson. She was the quiet one who ALWAYS followed directions until then. She didn't get in trouble, but they did call me up to school. Her teacher knew about the medications, and the reason why (her brother tried to kill her), and they thought it was truly sweet and funny to see her get all the kids into a conga line dancing. Only Jess.
She didn't take another dose of the medications after that. She hasn't had any need for them. Now that she is an adult, I would have no problem with her trialing antidepressants if she needed them. Children just don't react to medications the way adults do.
I don't tell you this to scare you away from medications. I told you to illustrate how different 2 kids in the same family can react to the same medication. Wiz actually took the same medication for years at the age that Jess took it and he never had a problem with it. It helped him greatly. You just don't know without trying. A short term trial is the only way to know if it will help or not.
You can ask the psychiatrist about a DNA test to find out which antidepressant is the most likely to work. Those were not available for us, but they are available now. Insurance covers them most of the time, I believe. Check to be sure, of course, but it could save a lot of time and trial/error. The test will not tell you how he will react. It will tell you which kind will be best for him, and which won't work for him.