If you suspect you have ADHD, try to find a psychiatrist/clinic specializing in adult ADHD. "Adult" is the key word here, general ADHD doctors are still focused on children. Finding an adult ADHD specialist gives you much better chance of not being ignored or pattern-matched to something else.

If you're worried it'll make you seem like you're looking for a diagnosis you'd like, be honest and up-front with them. Say, "I have a hypothesis that I have ADHD, I'm looking to have it confirmed or rejected, and in the latter case, to be directed towards a better one. Here is why I believe I may have ADHD...".