My boyfriend is a selfish lover... how can I tackle this issue?

I feel like my boyfriend is a selfish lover. I don't know if he thinks he's spending enough time on me or what but he's gone down on me twice in the total of our 5 month relationship and usually turns me on just enough to have sex. He's amazing in every other way but I don't know how to approach the issue... I don't want to ask him to go down on me if he doesn't like it because I wouldn't want him to do that to me but I'm so unsatisfied! He comments that I haven't orgasmed through sex but I don't think he's really ever tried properly to make it happen for me. Could someone advise me on the best way to talk to him about it?