The body grows and stops growing in response to the complicated interactions of all of its systems. It's not as simple as "add one hormone, get a certain response."
Also, if you are an average guy and believe that somehow your penis size reflects your self worth, frankly please re-think this mental set. Men who don't understand what women like try to rival each other in penis size, but women could not care less if a guy's penis is longer than average. In fact, too long and it hurts, because her vagina isn't that deep. It's not a beauty game, it's not a dominance game, it's what you do with what you've got.
If someone has a genuine 'micropenis,' it's possible he would want treatment for hypogonadotropic hypogonadism. But even guys with micropenises can please a woman, since all the nerves in her vagina are in the first third anyway.