The sippy cup is a good idea, something that can not be related to the breast at all, your DS wil be able to work up to feeding himself and then there shouldn't be any confusion. Depending on the type you choose you may need to take the 'anti spill' thingy out so they get used to it being a way to get milk because they don't always catch on to needing to suck it for a little bit. Once they realise they get a drink from it and they learn to suck the spout you're good to go. That's just from my expereince with learning to use sippy cups.....