19 and looking for diagnosis, how do i start even?

So I've struggled for most or even all of my life with Adhd and have been asking to get diagnosed even when I was around 13. The parents/adults in my life just were usually dealing with their own things so I just kind of fell of the wayside and didn't get support and was told alot I was "too smart to be acting this way" or "wasn't trying enough, like you don't even care". I'm realizing this is pretty common and I'm not too much of a freak, but now I really know I need help and its going to have to be me to do it now. Wondering where do I start with this? I didn't go to the doctors regularly ever as a kid because of unintentional neglect and skepticism from an immigrant dad so I don't even understand the whole medical system as a whole. Should I go to a therapist first for the neglect, then go to a psychiatrist for help? Should I get the diagnosis first? Sorry this sounds really scattered I don't usually ask for help out of fear so this is very new to me but I want to try. What comes along with a diagnosis?