I think I'll be alone for my whole adult life

I'm 23 and I think this is the best I'm going to get at functioning "normally." I've had social anxiety and OCD since I was in kindergarten and I developed selective mutism twice, the second time being in high school which resulted in me not speaking to anyone outside of my family for years during my adolescence. I've improved significantly with medication and exposure therapy to the point where I can converse with a stranger but the one thing I still cannot do is talk properly to people whose opinions I actually care about or want to impress. I'm in college now after flaming out and taking a several years' break and I made one sort-of friend for the first time since middle school and I don't even want to meet in person because it's just anxiety-inducing. I clam up around my advisor who is also a professor I actually want to talk to (she is in a field I am very interested in but I lose my speech likely due to fear I'll say something stupid) so I am having trouble even discussing my degree.

I haven't showered in three weeks now and school is either too easy or something small will feel too stressful. I'm not struggling academically but I can't network, which is just as important as grades apparently. If I manage to get hired in my massively oversaturated field, I'll be so exhausted after being at work around people that I won't want to try to make friends or even find a girlfriend during my off hours. As long as I have my mom to talk to and spend time with it shouldn't be too bad but now I can tell she's becoming concerned my social world is too small and even told me it would make her really happy to know I have people I can rely on other than her. I have my dad too, but our relationship is a little strained (at least on my part). I also have my brother but he's living his own life with his own friends and problems and stuff and isn't as interested in being close friends like when we were kids. I also talk to my grandparents but they're getting older and frailer and I'm pretty sure they won't be around to see me get married if I ever manage that, which is a really sad thought. I was also recently told by a psychologist I meet criteria for level 1 ASD but I'm not sure that's accurate.

Just the other day I realized, well, I'm probably always going to be alone in terms of friends and hypothetical wife. There's probably someone out there like me but they're probably on the other side of the world or something. I don't actually feel as bad as I probably should about it but I know it'll hurt when it actually happens. I'm about 300 miles away from home and go stir crazy because I don't talk to anyone aside from one like one sentence every other day or when I'm talking to myself or my mom on the phone. I feel like a loser because I'm a whole adult and I'm acting like a 14 year old.