im in a relation ship where i love and want to share myself. we have sex but it doesnt feel like it comes natural. is it because we are beginners or is it a bad match? it just seems like i can never find the right possition to get good penatration. and when shes on top she goes up and down to high and i will come out of her and it gets frusterating. im 5 1/2 to 6'' big but does that make a difference how good my sex is?