ive masturbated when i was 13 years old and when i was 14 i did it almost everyday for like 4-5 months...and now ive been doing it like 2-3 times a week....during sex ive noticed i lost my erection a couple times...and when i was with a different girl it lasted longer....is this because of the time before, the girl that i was with...or anything like that because the second girl i talked alot with her...does that lose your erection when you are having sex when u are losing interest in what is going on....i havent masturbated in about a month...and now i dont know much but i feel like i cant last because of this time i had sex...please give me some advice on what i should do....