Baby sleeping too much??

My son is 11 weeks old and I am very concern that he is sleeping 'too much' I mean he does eat. But his naps are longer with the same amount of intake (breast milk) which I have been pumping to make sure he's getting enough (5oz) every feeding. I have noticed he feels lighter too but also a bit longer, I didn't think much about it until my mother came to visit and also mentioned his weight. Should I be worried? I have tried to wake him up to eat today but all he wants to do is sleep. Any advice moms?