Suggest Treatment To Increase The Penis Size

hello my name is alex. i am age 19 and i have waited for puberty to make my penis bigger but it still looks the same since i been a child. i got all the puberty signs pubic hair,facial hair,leg/chest pretty much everywhere. i am depressed and scared. my question is should i see a doctor? and if so can he help me at all? i fear i have waited to long.