Hi, Richie! Welcome!
I'm a noob here, too, and pretty much where you are in real life, regarding your transition (only I'm, like, at least fifteen years older) but I haven't started dressing like a guy, binding, or HRT yet because I don't have the money, and won't till I get a job. I've got the name that I want to be called picked out, but that's pretty much it.
I know how it feels to be standing on the cusp, ready to just go for it, but not quite have the tools.
And I haven't told my mother, either. My friends, yes. My mother, no. It's a tough conversation to begin. But when your time comes to tell your father, you'll be up to the challenge.
I wish you luck and success in whatever you do. Especially in telling your father. And don't worry: in the grander scheme of things, high school will be a blip on your radar. It's a mere training ground for the wider world. You've survived it, so far, so you'll be more than strong enough to handle transitioning.
MJ-but-just-call-me-"Ethan"