This dude has way more problems than gender confusion if he’s 19 and still in HS. I graduated from HS at 17. Then took large college loads so had a degree and my first real job at 20. No, wasn’t a whiz kid, but just an average teen who thought it was more fun to goof off at college than waste summers back home.
I graduated at 18. But still, yeah, I would hope that he really works on graduating out of there and moving on from it, before worrying about his other issues.