My fear is, he has been doing well in other aspects of his life and if I push for him to stop or begin taking things away, he may rebel and it will be a slippery slope all downhill.
I have had the same issues for the past 8 years.
I share your concern. When I have made strong boundaries over my space and repercussions into my life, my son has ended up homeless, in a downward spiral.
I have posted here over 4 years. The mothers here have urged me to take a more moderate view. They have advocated that I allow my son home (I have a second home where he can live, apart with me, and supervised by a friend.) Why? Because I suffer so when my son is on the street. And my son needs support. He does have psychological issues.
This is the thing: We can't cave completely. We do ourselves and them no favors to accept anything and everything. To betray our own values and to give up on what we need, in our environment and for our peace of mind, is wrong. There are always bottom lines in life. We do no favors to our adult children, to give up our own bottom line. But that said, it's not so easy to know your bottom line.
In my state marijuana is legal. But I still have a right to insist upon no drugs and controlled substances in my home or in property that I own. I have accepted I cannot control my son's marijuana use. But I can insist he is not visibly drugged and that he not bring drugs into a property that I own. (This has been impossible to enforce, up to now.)
I have requested that my son get a drug test, now that he is back. A real one. We are working on getting his state ID which is required. He really, really did not like this, being curbed and doubted. Good. Up until now, I have not asked for money for rent (he does not have it) and I am buying his food. Given all that we have gone through for years and years, I believe I need a baseline to see how bad is the situation we are dealing with. I have no legal right to this. But I am his mother. I need it. If he doesn't like it, he can leave again. That's his right. For now, that's my bottom line. It may change.
I guess that is what I am talking about. We have to find our bottom line. And it shifts. It's different for each of us, and different for each adult child.
To close, I share your worry. There is no easy path here. No right path. It is trial and error. They want to have autonomy and to believe that they control their own lives. (While they depend upon us.) It is inevitable that they will make mistakes. We will feel powerless and that we lack control. We will decide each of us how much we can take, and how close in we can be. There will never be a "right" thing to do at any given moment. We do the best we can. Until (and if) they find their bearings, and begin to make better choices.
Meanwhile we post here. In my experience, there is no other way. For you, it may be different. I hope so.
Welcome. Take care.