Is she eating enough?

My lo is a week old now and was eating 2oz from the ready feed formula bottles but was spitting up a lot so we switched her to the phillips avent bottles and she is now only eating about an oz every feeding and going about 2 hrs between feedings. Her spitting up is doing much better now its barely at all but i feel like shes not eating enough or getting the reccomended #of oz a day. She just doesn't seem to want more than an oz, its not because she falls asleep at the bottle because she turns away from the bottle after eating even if shes awake or after i burp her. Is this okay? What should I do?