i'm a 25 year old male and ever since i've been 17, about 90% of the time, i lose my erection before i can actually have intercourse, and even when i can get fully erect, i lose it during. even when i masturbate, i'm not usually 100%. although i can and have had full erections, sometimes it's just a c**p shoot. although i've been with a handfull of attractive partners, when it comes time to do the deed, i'm just not up for it no matter how aroused i am mentally. help! i should be in my prime!