I don't think its normal, no. Oh, I am sure many boys would LIKE oral sex twice a day. But they have the restraint not to constantly ask. What does he think, that you are a ready-made blow job machine? Can he honestly think you want to do that every day,twice a day because he asks for it?
And you don't even want to do it all the time, what is the matter with you? Don't do it if you don't want to.Grow a spine and say, 'not right now.' If you are afraid he will break up with you if you refuse, then at least you'll know for sure what I already suspect: he's using you and doesn't care a whole hell of a lot what you want or feel.