I was in my mid-30's when I got my diagnosis and that was the first I'd heard of it.

There isn't a test. It's usually a fairly long period - weeks or months - where the doctor gets to know you and rules out other conditions. Don't try to edit your answers to get a quicker diagnosis, because it could be you have something else (the DSM is a big book after all, you can't have seen it all) and if you're misdiagnosed it will just take you longer to find the correct treatment.

Basically the only thing I got from the diagnosis was relief that I wasn't the only one that felt that way, that I might be odd but I'm not unique. There is no cure for avoidance, only learning ways to manage it, until it figures out the way to swamp them, and you start over again.

If you have the full blown PD. You could have traits, and those can be positively affected by CBT.