I cannot have an orgasm.

I cannot have an orgasm. Not through intercourse, not through masturbation. I have tried so many different things and I cannot do it. I've been sexually active for about 5 years now with 3 different partners and none of them have ever made me cum. My currently boyfriend of a year tries very hard: goes down on me, clitoris stimulation, everything. I think something is wrong with me and I really just want that feeling. I hate faking it. Please give me some advice.