Hi,
My dd was (still is!) breastfed and never took a bottle. I weaned her off the mid-day feeds at around 13 months. She had been taking water no problem from a sippy, but also balked at milk in the same sippy. What worked for us is a straw cup. I've read that some breastfed babies prefer a straw-type sippy as the action is more like breastfeeding. So the straw cup (Playtex makes one) become her "milk cup" and she continued using the other sippies for water.
There's really no point in trying to get your lo to take a bottle now, since you should wean from the bottle at one year anyway. Just try some different sippies to find one that works.
Oh, and don't be surprised if your ds doesn't take much milk at first; my dd didn't. What finally got her hooked was mixing her milk half and half with drinkable yogurt (so it was very sweet and yummy), then slowly decreasing the yogurt until she was only drinking milk. Now she loves her cup of milk.
HTH!