So we have been using the enfamil newborn 2oz bottles ready to use since our little one was a week old. But now he's eating about 3-4 oz regularly so it's getting pricey. For the last 2 feedings I switched over to the powder. He hasn't wanted to eat much of it, just 1.5 oz and then when he had the 4oz he woke up an hour after, usually he sleeps 2-3 hours with that much. Right now I just tried to feed him and he spit most of it up and is acting hungry but doesn't want to eat the bottle. Is it really just because we are using the powder??? Anyone have a similar experience or thoughts?