My wee man is not feeding much during the day. ...

My wee man is not feeding much during the day. He is only drinking between 60-120mls formula each feed which can be anything from 4-5 hours. At night he is drinking between 100-140mls 3 hourly, 9, 12, 3 & 6. He isnt unhappy so I just wonder whether it is just a phase. He is also catnapping during the day so trying to get into a sleep/feed/play routine is impossible. Is anyone else having the same problem? Nat