That's where I was a few years ago (now a college frosh).
Work out, get yourself a swing coach/consistent lessons, and PRACTICE YOUR SHORT GAME.
If you do those 3 on a regular basis, you'll most likely end up at college level. The difference, for me, between my game at the end of high school and the golfers on my Patriot League D1 school's team (not Army or Navy, either :) ) was the short game. I had no problem tee to green... I'd hit like 85 to 90% of fairways and about the same % for greens, but unless you can make the up and down to save par when you get in trouble, you most likely won't make D1 golf. Also, 3 putts are a score killer.
The biggest takeaway for me from my time on my high school team is that I should have worked my short game harder. If I could do it all again I would work so much harder on chipping and putting. I'm told all the time that I have a beautiful swing, and people wonder why I don't play for the school.......that's the reason why. Didn't practice short game enough in high school.
As far as skimping on one of those 3 if you have to; definitely working out is the one you can neglect most often. I am 5'9" and 135 lbs (skinny as a rail). The extra distance you'll get from being stronger is certainly nice, and can help in some situations, but it's not game breaking like the consistent lessons and short game are.
EDIT: PGA level golf is a big dream to have, so good on you for it. I don't want to be the rainy cloud, but very very few people get to go PGA. Even some of the D1 golfers from college don't; and I'm talking about powerhouse D1 schools where they can golf all year round.