Which Shampoo you are using? what it is made of? if pubic hairs are build from DHT, your shampoo should reduce pubic hairs, why not try it. I bet it dont reduce pubic or armpit hairs. so think talk about penis growth and scalp hair growth later. but dont worry, you will get some reason to blame if you expect penis growth after 17 but its still same size as in 17. make sure these 3 things- smoking, weight gain, no erections for long time.