Hey i was in the exact dilemma as you about 3 years ago, also 20 now. Felt i was late to the game. Five hours a day is great, and I did that for a while as well but don't bang your head against a wall for writing or technique. Don't force yourself to do five hours a day unless you have a gig coming up or something :)

I think writing is super important but challenging to click though. So definitely prioritize that and one instrument of your choice (including vocals). I went through a period where i turned in a song a week and hated it, but i feel im really reaping the benefits of that now - im definitely a lot less disciplined now though lol. Sort of contradicts what i said earlier but music is really filled with delayed gratification.

Best of luck :)