You don't need to have any official diagnosis to find help. If you look at the issues you are struggling with, the ones you want to work on, well, you can look that up online, in forums, self-help books, setting your own challenges, etc.

Personally - I started setting myself really small challenges. I've worked my way into bigger ones over the years (.... about half my life now, actually). There are still tons of things that other people might not even consider to be stress-inducing that still... just can't get done by me.... but other things that tons of other people can't handle, I can do now. It's weird, lol. But I've kept, and keep, pushing myself to where my limits are. Sure, I'll fail and chicken out a lot. But I just keep on trying. (I do, however, primarily set myself goals that don't need to involve anyone I actually KNOW... so... haha...)