Hi Doctor, I Had My First Sex With My Wife.

Hi doctor, I had my first sex with my wife. During my sex, my penis got erected and its standing still for many minutes, but I am not getting the final pleasure for sperms to come out. When I mastrubate, I get my sperms. My penis is strong n fit. I don't why I m not getting the final pleasure, I am not sure whether my wife vagina hole is big because of that the friction between the penis n hole are not making me feel. Please do reply