Most Helpful Girl
Your not the only chest hairless 19 year old. my brother nor any of his friends have it either.
Chest hair usually develops later on in most guys. Some guys get it early, but it's usually later than earlier, or they don't get it at all.
A shirt wouldn't inhibit growth, as the nourishment and cellular structure needed for hair growth thrives in the skin itself.
So yea, you'll probably have to wait a few more years - or draw little spirals on your chest with a sharpie :P