I discovered I was nonbinary through a much more roundabout way personally. I had a gender crisis in high school, but I only knew about the full FTM and MTF kinds of trans. So since the idea of being a girl distressed me just as much as the reality of being a guy I figured that I wasn’t trans I just hated “traditional masculinity” until like almost 20 years later when my now wife went “That sounds nonbinary to be tbh” and I had some googling to do.

I did however go through a very similar progression to figure out I was Ace albeit without the car crash though. Good old “Straight is the Default Right Guys?” then “Huh … I don’t actually feel any different about men and women, do I? Must be Bi lol” into “Yeah dumbass, you don’t feel any different because you do like both men and women the same amount… fucking 0” to finally “Okay, upon further review you are open to reciprocating affection from basically anybody as long as you are attached to them enough emotionally.”