I was fortunate enough to get evaluated when I was describing symptoms to a psychiatrist [I was at an outpatient clinic for depression/anxiety meds, which is what Medicaid was willing to pay for] and he started asking me about childhood stuff and he was like "you sound like a textbook case of inattentive ADD, let's take an evaluation quiz". I can't take stimulant meds either [I do self-medicate with caffeine] and I was already on disability so the dx was just one more thing in the list of "here's why this person can't function in a way that befits having a normal nine-to-five job" [some people with ADHD can, obviously, but] but it was, like you said, emotional validation. Suddenly a lot of stuff made SO MUCH more sense and all of the "stupid and lazy" comments I got from my mom and others, welp, that's executive dysfunction.

I mean, I think self-diagnosis is valid in this case - almost all AFAB people I know of a certain age who have it [and/or autism-spec] weren't diagnosed till adults if at all, it was absolutely underdiagnosed with Xer and millennial AFAB people in those days, and it's one of those "if it looks like a duck, quacks like a duck, walks like a duck" type things IMO - but if you really want the piece of paper it's very understandable and I hope you can find someone to dx without too much trouble or expense.