giving boyfriend head

I've never given oral sex to any other guy before so I'm not sure that my BF's reaction should be any different than it is now.

Can anyone tell me if his reaction is normal or give me any other advice?

I've touched my boyfriend and given him oral sex multiple times. However, he never seems like he's enjoying it and acts like he's falling asleep. I've said something to him about it and now he tells me that what I'm doing feels good but he uses the same bored tone of voice when he tells me that as when he is talking to his mother during dinner. I mentioned it to him again and he says he just doesn't know what he's supposed to do.