Academically gifted?

I am undiagnosed and suspect I could have ADHD and/or Autism because I have several symptoms related to these conditions. However, whenever I have discussed this with people-friends and family, they tell me I cannot possibly have any of these since I have a very good academic record. I have a bachelors degree in Biotechnology as well as an M.Phil in molecular biology. And not just this, I have been at the top most of my life and achieved much more than simply a degree.

Yes, I have always had extreme struggle getting myself to actually study. So I just did not study throughout all these years. I used to skim the syllabus just hours or typically the night before any exam. That is how I was able to complete my degrees. (I did not miss classes.) I also was never ever able to complete the syllabus for any subject before any exam.

Anyways, I am making this post to have an idea, are there people who have a good academic record and are officially diagnosed with ADHD, Autism or AuDHD? I've come across some news (from social media) that this is a common occurrence.
If yes, how has being academically giftes effected your diagnosis process?
How is your relationship with studies?