“If I’m passionate about something, I can focus…” That describes the ADHD nervous system — it’s motivated by interest and urgency, not importance.
You can certainly have ADHD without being “fidgety” or hyperactive. It’s called ADHD Primarily Inattentive now (used to be called ADD).
The next step would be to contact a clinician for an evaluation.
ADDitude Community Moderator, Author & Mentor on Parenting ADHD, Mom to teen w/ ADHD, LDs, and autism