You very well still could be. Diagnosing conditions like these is very complicated when different things can present similarly, or even mask each other depending on their presentation. Autism and ADHD have a lot of overlap for example where it's not uncommon for someone to have one and be mistakenly diagnosed with the other because of how their particular combination of strengths and deficits manifested. Then still other conditions can mask symptoms entirely that without them no one would ever guess that someone might have ADHD.
That's what happened to my wife in fact. She joined a research study that was aiming to improve diagnosis for ADHD looking to be part of the control because she was reasonably certain she didn't have ADHD.
We come to find out through participating in that study that no, she did in fact have ADHD and her severe OCD had just been masking it all her life. The second she got on a new medication that got her OCD more under control I got a front row seat to literally watch the things I struggle every day with just manifest in her like I'd given her the damn Curse of the Were-Fuckup.