Try a bottle that's more like breast, my baby hates bottles she will tolerate the munchkin latch bottles if I'm not around
Make sure the milk is a good temperature. Don't give up. pump 2oz and give him the bottle first and then breastfeed. Always start with the bottle when he is hungry. It may be easier to get someone else to give him the bottle because he can smell you.
I started giving my baby a bottle at 1 month because I knew we would be traveling. I use Dr. Brown but I have heard some moms say that agent has nipples that remind baby of your breast.