L.K.
N.,
The milk sitting on her teeth all night is VERY bad for them. If you want to continue giving her the milk in the livingroom before going to bed, I would add brushing teeth right after and just before sleeping as a regular part of your routine. Other than that, it sounds like you're doing great. Don't be afraid of change :o). You're right, kids get used to things Much more quickly than we do and it's actually pretty hard to make that big of a mistake.
L.