Why do I feel so different from everyone else?

I've had a hard time with friends and socializing since middle school. I started experiencing some abuse from my parents around that age and that's honestly the last time I thought I was somewhat normal. That's also around the last time I had an actual group of friends.

I've dealt with depression and anxiety since then, and have constantly felt so different from everyone. It feels like I had to grow up 10x faster than everyone else, and its been hard connecting with people my age. Whenever I see people who seem "normal" I get this huge sense of shame and try to hide myself feeling like I'm weird compared to them, its like they live in a completely different world. I think they'll pick up on my awkwardness and lack of social skills and judge me or treat me different. I've isolated myself for a long time cause of this.

The only time I feel more confident in myself is if I'm around people I feel more "normal" than (I know this is kinda hypocritcal, not very proud of that) This has led me to having some pretty bad friendships recently.

Before anyone suggests I dont think its autism, my therapist said she doesnt think I have it. I have wondered if I have cptsd/ptsd though, not sure if that would explain this.

What is making me feel this way? Can anyone else relate? How do I stop feeling like this?