Feeding at breast is an active process, requiring babies' effort & exertion. Bottle feeding is mostly passive, just tongue to control flow. So, breast feeding issues are tricky: problems can arise from mother: poor positioning, inverted nipples, poor hygiene, etc; baby: nipple confusion, poor effort tolerance denoting serious sickness, poor oropharyngeal muscles, oral candidiasis, etc. Best is to approach a lactation expert or your Obstetrician.