I get a little support from an in-person support group. A little feeling of belonging but not enough to really sustain me and most of the other folks are not real functional either! Not surprisingly.
I've found some emotional support here on PC. Lots of variety of different opinions including folks who don't seem so dysfunctional as the people -- whom I love -- in my support group, most of whom had dysfunctional families, too. That helps, as I try to become more functional myself.
Please keep on trying. I can believe that it's very hard. I understand what the doctors are saying and yet -- it's a deficit in the system for more people than they realize, maybe. Even if yours is exceptionally difficult.
Sounds like your mind is working pretty OK, though. That's a toughy for me sometimes because when I get to feeling too bad or anxious it certainly affects my mental state.
But the main cause of distress, for me, is the loneliness and alienation. And shyness, awkwardness, extreme hypervigilance and social anxiety even though I do go places.
I was luckily married for 24 years to a somewhat similarly geeky guy, but he died. And it's been lones-ville ever since.
So finding a partner may not be so impossible. It's difficult for most young people, just especially difficult for you, I'm sure. But it may not be impossible.