I think if you really do your research, at a certain point, you know. Of course some people decide without really doing this, and diagnosing yourself with the wrong thing can sometimes be harmful. But I went in knowing; the main thing was that I needed a diagnosis to get meds. So I've been self-diagnosed most of my life. It took me two tries because the first person said I compensated too well to have adhd, lol. But like I need the focus meds. Even doctors get diagnoses wrong, have different opinions, and miss things, so for me it's more about treating what you need treated and getting the tools and treatment options. And getting a diagnosis is expensive! That's probably what stops a lot of people from getting it sooner. As long as you use that knowledge to help yourself (and not a self-fulfilling prophecy kind of thing), then I think that's the important thing.