Hi Elvet,

Beard coverage and growth is a function of age. You are still young. However, you have seen big changes as you noted each year. I think you will continue to see more development. Masturbation will not effect your beard potential. So don't worry about that. You have plenty of hormones given you have facial hair. If you want to increase  testesterone then eat healthy, sleep, reduce stress and do weight resistant exercises. Is that your beard in the avatar? It looks good for a young man. When I was your age, I had a short goatee and mustache. My best facial came along in my 30's. My suggestion is to grow what you can now and be proud. Grow what you can and have fun. There are lots of options. Good luck.

Erik