Ryan has reflux and when he was younger he was the same , we did increase the oz 's of formula in a feed , we thought he was constantly hungry . thinking back now though we figured it was that he wanted to drink all the time as it soothed his throat . he had bad reflux , still to this day he drinks loads of water in the day. so it could be that your LO is still hungry but it could also be a way of soothing the throat