I'm a first time mom so maybe this is silly... I know you count ounces with formula, but how do you count when you're breastfeeding?

There are no silly questions in mamahood. :) If at some point your pediatrician is worried, many hospitals have a lactation consultant on site that you can visit (or they can sometimes visit you at home for free, depending on your health insurance). They’ll weigh baby before nursing, then have you nurse, then weigh baby again after. The difference is the number of ounces baby drank, which they’ll use to see if baby is getting enough milk while nursing. But this is usually only if they’re worried about weight!! If you’re breastfeeding and everything looks good with baby when you leave the hospital, they’ll tell you to count the number of wet diapers, and that will tell you if baby is drinking enough.