Heavy Eater

Bambi
My baby, 5 weeks, woke up around 1230 am, and I fed him from the breast, normal amount. He awoke at 330 am, fed him 5 ounces of breastmilk from bottle, but wanted more within an hour. We had to feed him 4 ounces of formula to get him fed, but he is still having problems settling down and sleeping. Anyone else have this experience?