Depending on the child, some babies are not going to sleep through the night until they are even one year of age. The sleep patter that he has right now is very irregular, but you can do a few things to help change it. Babies are still going to have minds of their own...sometimes it's just waiting it out that is all we can do.
He could be going though a growth spurt, in which case she is going to want to eat more. He may just need more to eat because he isn't getting enough in the first place. You can increase his intake during the day.
All babies need a certain amount of sleep for their age range. If he is sleeping too much during the day, he is using up that sleep time that he could be getting at night.
I have had some children who just don't need that much sleep...and there was nothing I could do about it. I don't want to discourage you, but I have seen it happen to other parents as well.
6 months: 11 hours plus two naps (1 1/2 to 2 1/2 hours each)
9 months: 11 to 12 hours plus two naps (1 to 2 hours each)
1 year: 10 to 11 hours plus two naps (1 to 2 hours each)