I first heard of it when a neighbor was describing her eight-year-old's behaviors and why she suspected AS for her daughter. Everything she said, I said, "hey, that's kind of like me." I think I even said "maybe I have that!" but I didn't mean it seriously and never gave it further thought.
But my associated issues (social, sensory, coping, meltdown) got worse to the point where said neighbor actually told my friend she suspected I had it. And eventually, I remembered the words (during a meltdown), thought maybe I should find out what it was, and Googled it.
Pre-Googling I was maybe 25% sure.
Post-Googling I was 95% sure.
Since then, three professional diagnoses and no one has said otherwise.
Incidentally, though I turned out having it, the eight-year-old girl turned out not to. Good thing her mother suspected, though, or I might never have found my own answer.