Boyfriend being selfish in bed

Been with my boyfriend for two years and never once had an orgasm. He's so selfish in bed!! I always go down on him and ladies I suck the life out of that dick but then I have to ask politely for him to return the favour! When we have sex it never lasts more than four or five minutes and I never get to go on top because it doesn't do anything for him even though it's amazing for me. If I tell him not to cum so that we can change positions he does it anyway! Sex has become a chore for me now and no matter how much I try and persuade him to spice things up he just wants his five minutes. I never get my happy ending! What do I do?