Yes I know this intimately. I was an extrovert once....
It is my opinion that you're doing the best that you can. Like someone else said, reminding ourselves that it is ptsd keeps us swimming above that line. And remember what Anthony said before, we will never go all the way down because we "want to survive".
I spent so much time alone, confined as a kid by an abusive step father...where I played board games and card games with myself. I literally acted as each player and carried conversations with myself. As an adult, I have a huge yearning to have that buddy to do everything with but people just don't seem to want that. It's discouraging and causes me to isolate further because it re-confirms what my step father said about me.
I don't know if this even comes close to what you describe. I also isolate because I feel like I'm a freak. The symptoms that arise when I'm out there in the world and not having anyone in person truly understand is so hard. People leave me when I isolate no matter how much I try to be so transparent and honest about what I experience.
Anyway, I really really just want someone to play with because I never got to do that but because people have responded so poorly to my "neediness", it has pushed me even further into isolation. I'm always left thinking what's the point. It's really tough when I feel like I have to fake it in life. What I mean is, it's not normal for me anymore to just go with the flow, I can't have one conversation with someone without being affected by a trigger. I can't go one place without it overwhelming me.
Please forgive me if this doesn't make any sense or doesn't have anything to do with what you posted about. I think I just rambled quite a bit.