This is similar to how I was. Up until I was about 16 I never really had any good friends and the idea that someone would want to ever date me was absurd. I would dwell over things that happened...replaying stupid things I said over and over and worry what others must be thinking of me. I had severe depression and struggled with self harm, and pretty socially inept and thought I was hideous.
In a teen group therapy session I was forced to go to, I talked about volunteering with dogs and dog training I did before I was depressed and also how much I hated myself and thought I was a shitty person. One girl in that group said "Well, I don't think anyone who likes dogs that much can be that horrible". That was the most positive thing anyone had said to me in a long time. So I just threw myself into the dog obsession and really became passionate about volunteer work. It helped me move past depression and be happier with life in general.
I also dropped weight and started dressing better. I made friends with a guy online (AOL) and started hanging out with him a lot. Unlike a lot of the people I would hang out with (who were druggies and didn't really give a shit about me), he was actually a good person and cared about me as a human. He "confessed feelings" for me but I wasn't into him that way, but we stayed friends and hung out a lot. His friends were all good people. I started dating one of his friend shortly thereafter. His friend was 20 and never had a gf; I asked him out on a date and we hit it off and have been together for 10 years now. We're all still friends.
So basically tl;dr