feeding questions

Ok my daughter is a month old and she just seems like she is eating way too much.... she will eat 4 ounces ever like hour and a half. I feel this is too much for her little body  but it's so hard to tell if she's actually hungry or just wants to suck on something because she always throws up after a feeding, she has since she was born and her doc just says "she's just a puker" ughh .. any suggestions or anyone going through this with there little one ?????