Maybe a long shot, but as someone with ADHD and self diagnosed autism, I would encourage you to look into the possibility. I struggled in school all the way through, constantly told “if only you applied yourself”, the problem was I was already working harder and didn’t realize the system wasn’t designed for my brain. Really the world in general isn’t designed for anyone neurodivergent, but your life still has value, you just need help figuring out how the whole unexplained thing works.
I have been Lemmy only since the 3rd party app thing also. I also stopped using Twitter when Musk bought it, and have Mastadon on my to-do list but I’m not sure if I want to spin up my own instance or make an account elsewhere. Other than that I have no other social media accounts and never have.
As for other Fediverse platforms, I’m strongly opposed to the for profit ones, but happy to see all the open source ones.