Desire and pleasure are linked but still very different. The more intense a desire you feel, the more sexual pleasure you'll experience, but it's easy to confuse sexual pleasure with orgasm.
Most women who feel sexual desire also experience sexual pleasure, but pleasure isn't just about the big O. Orgasm is the physical expression of the peak of sexual pleasure. Our natural reflex is to get rid of sexual tension by achieving orgasm.
If you can't get to the final level, and the pleasure you've experiencing isn' as intense as normal, or you're not getting good enough orgasms, then maybe your partner isn't doing it for you the way you like it, or perhaps you've got reservations that are stopping you from letting go for really mind-blowing sex...