I was diagnosed with ADHD too, but as a kid. I got on medication but my parents discontinued because it was harming my mood. It made me look so sad and I didn't smile as before. I wouldn't eat as much either. It's really interesting because I can't focus on things that don't interest me, but in the ones that do interest me I focus a lot. I usually get good grades too but didn't like math and got mostly B's and C's.
a possibility may be that you are gifted and your ADD symptoms were in fact because of boredom. I got my IQ tested and I scored very high, but the ADHD is still there and gets in the way.
Maybe, in your case, your ADD is very mild.