L.O.
J.,
I breastfed all four of my kids. The beautiful thing about breastfeeding is your body makes a perfect supply of breastmilk for your baby depending on the baby's needs. You probably notice how she'll nurse more frequently at times. This is an attempt to encourage your body to make more milk for her.
When you nurse her from your breast, you have no idea how many ounces she is getting. If she's happy, content, healthy and thriving then you can rest assured she's getting enough. Try to apply that same mentality to your expressed milk. Don't worry about the ounces on the bottle. Chances are that if you are giving her your recently expressed breast milk, it's going to be the perfect amount for her needs at that time.
Relax and enjoy every second with her. It goes way too quickly (as you probaly already know)!