I was diagnosed in high school, it’s fuzzy on the exact details because I was going through a lot of trauma at the time. I stopped being treated for it after high school, and only got back on the medication after having a suicidal meltdown and getting diagnosed with bipolar 2. Then I got rediagnosed as an adult

So in essence, I got treated for comorbidities first.

I had a neuropsychological evaluation ordered by my PCP. It worked out okay, but if I knew then what I know now, I'd have found an ADHD knowledgeable psychotherapist who knows the right psychologists in your area to do the testing. Psychologists have their strong interests and specialties, so going to a so-so one who doesn't truly understand and empathize with ADHDers could turn out badly. Part of the evaluation is interviewing, so it's not all based on answers to tests. Having the right professional can make a difference. Best of luck! ADDitudemag.com and ADD.org have lots of resources and *I think* have directories for ADHD knowledgeable therapists and doctors.

P.S. ADD.org offers virtual support groups for all kinds of situations. The groups are moderated by ADHD coaches who often have a wealth of knowledge and resources at their fingertips. There's a $5 monthly membership fee. IMO it's worth it. Talking to others experiencing the same issues often provides info and tips I didn't even think to ask about