I have to take your story with a big ol' bucket of salt, because you ignored medical professionals, and then tried to self-medicate with un-prescribed drugs of unknown dosage.
This is a controversial subject though, so I'm going to step out now. Just wanted to share the story of my negative experience with it.
Your experience is an indictment of bad psychiatry, which nobody here would defend. But you explicitly say you wouldn't trust them to diagnose you with anything (I wouldn't either), so I'm not sure why you then draw the conclusion you did:
> So I definitely think this whole thing is a huge pharma scam at this point. I'd be highly skeptical of any ADHD diagnoses
(FWIW, your comment is gray as I write this; I didn't downvote you, but I wanted to explain why I think someone might have).