My LO is 4 weeks old and is drinking 4-6 oz. I pump and feed and supplement with formula and have been using the 4 oz Dr. Brown bottles. Most of the time, my daughter will drink all 4 oz and still act hungry 30 mins later so we'll give her another 1-1.5 oz and she'll be wide awake until we top her off with another oz. I don't know about any of you, but that seems like too much for a 4 week old. At this age my 1st baby was a solid 3 oz and didn't need to be full to go to sleep. Is anyone else's baby eating this much and/or needing to have a full belly to sleep?