I had a large little boy, who was 18lbs at 4months, and they were asking me about overfeeding him
so they gave me some recommendations for feeding....
From what I've read/they said a baby should take in about 2.5oz a formula per pound of body weight but to not exceed 32oz. They also talked to me about over all calorie intake
Formula contains 20calories per oz of formula, and again, from what they told me a child 0-6months of age needs 50calries pound of body weight.
My doc did recommend starting solids around 4months because we did start to creep over that 32oz mark. Once we did that, the formula intake did go back to around 30-32o per day. I know that the recommendation is normally not to start solids until 6months, but just sharing what we did.
I'd ask your doc if you're concerned. It does sound like 45oz is a lot of formula, but I've never dealt with a reflux baby....and on top of that they always say each child is different