Very few women can cum from just simple intercourse or fingering.... it generally takes quite a bit of clit stimulation and even THAT can sometimes not be enough. I'm like that. Sometimes you just need that little bit of extra somthing. I would try some vibration, a clit stimulator or somthing to that effect. As you sound fairly young, or inexperienced, you might try the back of an old electric toothbrush (like the cheap ones by crest). Other than that just kind of relax about it. If you're so tense worrying about if you're gunna cum or not, you almost assuredly wont. When your doing stuff, relax your body, close your eyes and concentrate on the sensations. Don't be focused on the potential orgasm, just enjoy yourself and whats happening in the moment. It'll cum (pun intended )

i guess it's different for every one, i've been with some women that will come only with oral but not fingering or sex. When my wife and i where only g/f and b/f we used to play a lot and she will come often with fingering, but now that we are married and have sex every day (lucky me ), she can't come with fingering no matter how hard we try. Why? we don't know. It's just like that, and she can't come with oral either just with normal intercourse. So it's different for every one like i said.