Hello, thanks for asking on healthcaremagic. It is recommended to exclusively breastfeed a baby uptil 6 months of age and then start weaning foods while continuing to breastfeed. The longer you breastfeed the better it is for the overall child development. Since the technique of feeding from breast and from a bottle is different for a baby, it finds it difficult to easily switch from one to another. Some babies totally refuse bottle if they have been exclusively breastfed before and there s no harm in that. The only thing is that mother finds it difficult to leave the baby with someone else for going to work or elsewhere. What is suggested is to try different nipples and someone other than mother to give the bottle. Since you have already tried all this it seems it wont work. You can start the sippy cup after 6 months along with semisolid foods with a spoon. There is no disadvantage of not using a bottle at all. In fact bottle can cause health problems like diarrhoea since the nipples might harbour bacteria if not cleaned and sterilised properly