i think every woman has her own way to feel sexual, sometimes she wont get excited neither by the same things or the same situations, may be you need to look for the right moment and bepatient, start slow, make sure you are not pushing anything on yur way to get into her and do it softly, you will moreless recognize when there is a spot you are stimilating and she likes it, dont be afraid to ask if she wants more, dont be afraid to slowly change the speed, but most important, dont be scared to make a mistake, after all i am sure you stil have a long way to know her body and her turn ons.