Sippy Cup Dilemma

Alright all you  mothers out there... I have a question, how do you get an almost 13 month old to kick the bottle and drink milk out of a sippy cup? she will take a few sips but that is it. I have tried the no budge method and all i get is one crabby baby!!! I am scared that she will get dehydrated. She will drink water out of a sippy cup, but any ounce that i can get her to drink i need to be milk so she can get the vitamins and nutrients she needs. i am not really sure why you need to get rid of the bottle at one. anyone know? i get the whole not sleeping with your bottle thing because of the tooth decay. but she drinks her bottle pretty  much all at once. so why have her slowly take a few sips throughout the day of milk, when she can get it done in a few minutes with a bottle? I see that as kids get older they need more nutrition from food rather than milk. So if she is only drinking 16 or so ounces a day of milk does it matter if it comes from a bottle or a sippy cup? I think i would almost rather give her a few bottles a day with just a few ounces of milk and then have her drink water the rest of the time out of a sippy.

i am up for suggestions or comments.

here are a few pics of a little temper tantrum we had this afternoon. this was probably the 3rd of the day... I feel like i am creating a crabby baby that was once a fairly easy child. Is it worth it?