hi sir , welcome to health care magic, I can certainly understand your concern towards the effects of masturbation but it s quite normal to practice masturbation . If may affect sexual performance as due to over masturbation, skin over penis gets thickened, and sexual stimulation may get decreased but it is not too much in your case so there is the least possibility . From the details provided by you I can certainly understand that you are having apprehension towards your first sexual experience, so I can advise you to be relaxed and stress free, spend more time with the foreplay and try to share your mutual fantasies to achieve orgasm I can also suggest you some medications like antianxiety drugs is escitalopram which can make you relax and stress free as you never had history of weak erection in the past you canalso follow master and Johnson s technique, in which your co partner has to squeeze the penis forward just before ejaculation so that which helps in standing erection for the long time This methods would definitely help you as you are too young to start on media actions like sildenafil. Consult your Psychiatrist for further information Post your further questions if any Thank you