Difficult to orgasm

Okay SO. I have been masturbating and can orgasm perfectly fine with myself doing it and I've been doing this for more than a year (I'm 18) my bf and I have sex very regularly and we go pretty hard and for long amount of time but I've only orgasmed with him like 3 times.....what should I do? He's starting to feel bad. Like even when he's goes down on me I don't cum.