Hi Doctor, I have been married since last 18 months so far I never enjoyed sex properly, reason when I enter my penis in wife's vagina it goes 2 inch inside and then my penis comes backside I am trying to push inside but it's not there only I Start rubbing and within less than 1 min I ejaculate. When I enter in vaginal that time erection also good. I have consulted doctor they advised me to take duralast 30 but I not got benefits. Pls advise me i am also I would like to know what should be the minimum length of penis mine is 3.5 approx is this is k?? I m waiting for your reply doctor.