My son is 15 days old. how much milk he should drink per sitting??? I am lack of breast milk. For every sitting, I used to give both breast feed and formula milk. But because of formula feeding, he used to get vomiting every time. Sometimes he used to vomiting both from mouth and nose. I am using avent bottle for formula feeding and the Nan pro is the formula powder I am using. Please pour your advice to avoid vomiting.