I did a load of research into autism and co-morbidity with adhd. I literally trawled the interwebs for information on autism and adjacent. Read anecdotal stories on which did help a lot. I think spending hours and hours going through comment chains and finding similar experiences helped me understand myself more than most books on the subject would have. Because it’s real people talking despite where I was reading about it.

Basically make a list of things that sound close to your experience and go read up on those, like I found out I have misophonia and light sensitivity, dyscalculia and dyslexia all from that research, I know that a lot of my quirks can be managed better from that knowledge too.