Ok i am 16 years old and i have a problem i think. When i am with my girlfriend and she wants sex i cant give it to her because my penis wont stay hard. When i first start to play with her i get hard but when it is time for sex it just gets thick. I think it might be the posistion {she lies on her back while im in between her legs} or too much masturbation Ok for instance before when we tried to do it i think i didnt masturbate for 3 days and we were outside behinda a building and when i tried to go in in that position it was not hard enough so i kissed and rubbed some more and it still was not hard enough so after awhile i jus stoped. So im worried because she wants to do it agian and today is friday i masturbated today and thursday once a day. Before that i didnt masturbate until Saturday, so i have been holding off for about 4 days without masturbating.My girlfriend wants to have sex but im scared it might not get hard but do i need to go see a doctor or do i just need some good ole viagra!