I went varsity for wrestling and I'm a freshman, so it's not impossible,
since your not in high school you should start training to get into shape. You got to outshine everyone when your trying out. Just keep working out and doing your best.
and for football you should start lifting but I don't think it matter about height. I recommend running a lot.
and wow you can dunk and your only 5'5, I'm only 5'3 and I can barely touch the net yet again I have no hops