My DD wouldnt take a bottle at all. In the end we introduced her to the cups with a straw when she was around 6 or 7 months (I think) We got them from Woolworths.

She would never take EBM though. She would sometimes take formula from my mum when I was at work... and that was the only solution we could find.

I spoke to ABA and they suggested I was being to "hesitant" with the bottle and that breastfed babies are used to the nipple being further down. Maybe try putting the bottle right in his mouth? (Didnt work for us but worth a try?)