Can't orgasm

I've been with my boyfriend for over two years and we have tried so many different positions/techniques and toys to try and make me cum. For some reason I just can't get there and it's so frustrating because he tries SO hard and I know he feels like shit about it. I just feel like im missing out and I want to be more intimate with him by getting an orgasm. For some reason masturbation just doesn't do it for me at all so it's even harder. Was just wondering if anyone has any suggestions?