The level of intimacy has built over the past week or two with a girlfriend of mine. We have tried to have sex a couple of times, but with little to no success. When I try to penetrate her, I am only able to get the head of my penis inside and almost nothing more. I am close to average in terms of size and girth. She is a virgin, but I don't really know if that holds any bearing at all. Any tips or advice on what I can do to help me penetrate her completely?