Caleb's First Bottle

Isaac gave Caleb his first bottle (of breast milk) tonight. It's a great bottle that has a nipple within a nipple to simulate the action of breastfeeding. Caleb ate 2 oz from the bottle then breastfed as though he hadn't eaten anything. How much can an 8 lb baby eat?!?  We'll be doing bottles a few times a week to help Caleb prepare for me going back to work next month.