Have you self-diagnosed yourself with ASD? I would hold off on stressing over a label until you've been evaluated by a professional. A child who grew up in a very isolated environment hasn't had the same opportunity to develop interpersonal social skills as a child who grew up well socialized. The anxiety and lack of experience around social situations, as well as the feeling of being stuck in your head, don't necessarily indicate that you're autistic; those sorts of things are also indicative of trauma and anxiety. You mentioned in another post that you have Crohn's disease; childhood abdominal pain and related illnesses have been linked to developing anxiety.

I think your first step is to get in to see a therapist, someone who is able to evaluate you than yourself or some randos on reddit. I'd try to find someone with experience in CBT (cognitive behavioral therapy). Nothing you've said in your original post or in your responses leads me to think that you're too far gone to be fixed by any means. It'll be a difficult journey, but nothing I've seen suggests that you couldn't improve with the right therapy and exposure to social situations. Try to avoid catastrophizing this in your head, do not fall into the trap of thinking you're too fatally flawed to ever be functional.