Not super useful input, but I literally just went through an adult diagnosis and can share how that went. There was a parent questionnaire about my childhood, school transcripts, a self-assessment and two 1on1 interviews. They basically just counted points based on my answers. And the whole thing left me a bit skeptical, a lot felt like interpreting a horoscope tbh.
Also there was a lot of focus on how much my "level of suffering" (Leidensdruck) is, which feels weird to me - if my environment is different and I don't "suffer" as much I don't have ADHD?
So no clue whether I have ADHD or not. But I did it because I want to try out medication under supervision to see whether I am able to take care of the things I struggle with more easily.