First off, congratulations on the fact that you are off the bottles and she is drinking well from the sippy. As you may have observed from many posts here, that is the first (and sometimes most difficult) battle. My 28 mo DD gets a sippy with about 6-7 ounces of warm milk twice a day. First thing in the morning when she wakes up (which she polishes off in about a minute) and then about half an hour before bed. I have thought about the fact that the morning milk may interfere with her breakfast, but the night milk is an hour or more after dinner, so it has no affect, unless, as you point out, she eats dinner really late and wants little of her milk at night. For us, milk is one of the few sources of either protein or hydration (DD is not a big meat eater and does not suck down juice or water during the day), so I consider milk something more than a drink, but less than food, if that makes any sense.