Hi,
Am facing the same issue with my daughther who is now just over four months. On day four she was hospitalized due to poor feeding and was immediately put on formula, which she happily took till she was about two months. Post that she has been refusing bottle and wants to feed only on the breast. We have tried different bottles, teats, milks but all in vain. She at four months has gained less weight then what she should have. I am trying to feed her now through spoon and cup but she hardly takes 5ml. I have also increased the no of feeding so that she gains weight. I was also planning to wean her, any advice. When did you wean your son?