I have significant social anxiety, as does my teen daughter. She tries really hard to avoid mistakes, as you described, so much so that it becomes paralyzing. We have found medication helpful for general anxiety, but it really doesn’t help social anxiety. What has been shown to help social anxiety is CBT (which also helps ADHD).
As for the ADHD, the clinician who evaluated you desperately needs an update on ADHD. You can absolutely have ADHD without any hyperactivity. It’s called ADHD, Inattentive Type in the Diagnostic Manual (DSM-V).
It sounds like you should absolutely pursue a 2nd opinion. Try to find someone knowledgable about all 3 types of ADHD.
ADDitude Community Moderator, Author & Mentor on Parenting ADHD, Mom to teen w/ ADHD, LDs, and autism