ADD is usually diagnosed through a behavioral checklist that both parents and teachers complete. You describe some of the attributes of ADD in your DS but his test scores don't present a typical ADD/ADHD profile. These kids usually test low in working memory and especially in processing speed. The scores I have usually seen are right around the average range (100) or slightly below. Your DS has well above average WM and PSI in the superior range.
Your DS' WISC scores do not match the typical ADD/ADHD profile. Generally undiagnosed ADD kids are also struggling academically and not achieving straight As. Neither of my kids have OCD and anxiety but is it possible that perfectionism and anxiety could be causing the task resistance and difficulty with timed tests you describe?
That's the limit of the light I can shed on this. Other parents who face OCD and anxiety will hopefully respond and give you more insight on those challenges.
