What is the answer? It is simple.
Some women enjoy sex, some don't. Some women enjoy a certain size, some don't care. Some women can become aroused and orgasm just over the thought of her man, some need something more "physical" to get her off. Some women couldn't get off no matter who they are fucking because it is within the woman herself, while some women can get off with just about anybody because it is within herself. I could go on and on...
The lesson?
Don't worry about it. If you find the woman who is right for you, none of this will matter, because she will either not really enjoy sex or care to get off, enjoy sex and get off with you, won't know how to get off and doesn't care anyway, does get off with you no matter what your size, and all or any portion of this is...
why you are with her in the first place! Otherwise, the both of you will split up and you will find another woman who is compatible with you.