I when I first came across Avoidant Personality Disorder I had a similar reaction. I like to joke that I see myself in every mental disorder, but with AvPD it really resonated. I came across in my late teens, around a decade ago now, and there are a few things I remember that stood out. The first was about the use of imagination - AvPD often has people with active imagination that they spend a lot of time exploring - which is something I did a lot. I was a chronic daydreamer. The other thing was how it differed from Social Anxiety. Whenever I would read about SA, it would focus on the anxiety symptoms -sweating, fast heart rate, panic attacks, things like that - and I didn't really face those issues very often. It wasn't because I didn't have a similar underlying issue, but that I went to such great lengths to avoid anything that would possibly lead to the slightest bit of anxiety I never got to the point of feeling anxious. And when I say ridiculous, I mean if I was walking and took a wrong turn I'd walk an extra mile so no one around me would notice I walked the wrong way.
As to therapies and self help, I've done them both. I think they can both help a lot. There was a time when I thought I would never be in a relationship, and I have since had a few. That I'd never get a job, but I managed to do that too. I sometimes think owning and maintaining a house is out the question for me, but I imagine I'll prove myself wrong there as well (at least for the non-financial reasons
I've always felt it's easy to believe that basic life functions are too difficult and I can't survive. I've gone through rough patches where I believed it so much that I stopped trying to survive altogether. But when I actually do try, things almost always end up being ok. And it tends to be something that builds off itself. The less I avoid, the easier it is to do things. The more I avoid, the bigger and scarier everything becomes.