The exact same thing happened to my son. I overproduced and had an overactive letdown so he got lazy and wanted the bottle instead. Just keep trying to put him to breast first then after a bit give him the bottle. My son never would go back to the breast after he got use to the bottle. Good luck! If anything can you just keep pumping so baby gets breastmilk?

@kambam, thanks for advice!

You can try a nipple shield to get him back on the breast but you cant use one forever.