Pyarrie,
your not alone out there with this problem. many many woman have the same thing.
working in the adult shop i hear many woman say this. you need to know your own body. a lot of woman can not reach an orgasam with just internal simtulation. some can not reach it at all unless its just clitrol stimulation. the clitoris can been very sentive more on one side then the other or just above it. some need both kinds of stimulation. There is also anal stimnuation some can only get there orgasam by having annal and internal stimulation at the same time. I have heard woman say that they feel like they are going to pee and then panic. This feeling has been known as the ultamate orgasma (female ejecultation) and they just dont know that what it is.
get to know your body on your own. The shower is a good place to do this as the water will stimulate the never ending in your whole body use plenty of nice soap over your body (not internal) get your self aroused then move to the bed room where you can then explore the inner you.
There is some great toys out there that you can use to help you. once you have found the right spot that does it for you. then introduce your partner to the magic spot go slow it will happen and I can tell you when it does it really will go with a bang.