P.S.
I'm breastfeeding, but I know until about 3 months, my baby ate really often. First it was every hour, then every 90 minutes, then every two hours. They say breastmilk is digested more easily than formula, but regardless, babies that young really need to eat a lot.
And you'll hear a lot of guidelines about how much and how often every baby should eat. They are just that--guidelines. In the end, you need to meet your baby's needs. For me, it was tough because nursing that often meant I couldn't ever go anywhere for a while!
Just be willing to try different things and know that there is no such thing as normal or abnormal, only what's right for your baby.