no climax

I'm 21 years old and have been masturbating for a number of years but have never been able to orgasm - no matter what I do or how long I do it for. I do have a boyfriend and have already explained to him that the big O doesn't seem to happen for me. However, I think he's beginning to feel disheartened that after a number of months with him I haven't had an orgasm.

I've been in a relationship for 4 years and I still haven't had my first orgasm. I've been faking it for all this time. How do I tell my partner and how do I get my first orgasm?