J.S.
Hi there. On the transition to the sippy cup... I was told by my local WIC office to put watered down milk in the bottle (start out slowly like 1 oz water 7 oz milk) Then after he's drank that (if he will, my daughter wouldnt after I put I think it was 2 oz of water 6 oz milk) offer him the sippy with ALL milk. (I stuck with the soft nipple sippys so it was still like a bottle, till she got to chewing on it...) He should want the sippy more to get that good tasting milk :)
Hope this helps! Good luck!
J.