I am 20 and have no breasts, not even a cup. I know I have hormone "issues" from my derma. But what should I do to help my breast size, also hair growth?

It's always wise to. Start by seeing your primary care physician & your gynecologist. Some genetic syndromes as well as endocrine system issues can cause lack of secondary sexual characteristics. You may benefit from evaluations by specialists at uab school of medicine to determine if you have a diagnosis for which treatment is available. Even though it may be a touchy subject for you, don't be afraid to ask.
Natural? Finish H&P. I would first complete your endocrine evaluation. Some of your symptoms are suggestive of pcos, what do you mean by natural? Non-surgical? Mechanical? Weight gain? Bio-identical hormones? Garments? Vacuum devices? Duct tape? "chicken-cutlets"? Pads? Exercises? Few of these provide sustained desirable results.