Any formula fed babies?

How much and how often does your baby eat? And how much does he/she weigh?

My baby is 11.5 pounds and eats 4oz every 3 hrs (4 months old). Sometimes she’ll act like she wants an extra ounce, but I’ve noticed when we do give her 5 oz she usually spits up those times. I’m wondering if I’m feeding her too much and should just stick to 4oz.