they don't 'like' milk from a sippy... because babies 'know' that milk comes from a 'nipple.' It is instinct.
Maybe just give her milk in a bottle. Or mix breast with milk, to transition her.
Whole milk is important and recommended from 1 years old... because the 'milk fats' in it is an important nutrient for brain development. Whole milk being the recommendation until 2 years old.
My daughter, well with both my kids, they self-weaned.
My son at 1 years old, and my daughter at about 2.5 years old. My daughter of course by that age, was drinking whole milk and eating just fine and drinking other things from cups. Too.
My friends, to wean their child from breast... actually put Band-Aids in their nipples... and told their child "Mommy has a boo-boo...." or "Mommy's milk is broken...." and they said this worked for them with no anguish from their child.
Also, with my daughter, when she wanted to nurse, I told her "In a minute, Mommy is busy..." and then I would NOT sit down and made myself 'busy.' Then, my daughter would get distracted or even forget about it.
OR, when your child wants to nurse... you can... but ONLY for a short moment. Don't let her just hang there. Shorten the duration of it.
each child is different.... so what worked for one child may be different or not work for the other.
Also, give your child a "Lovey" to comfort with and to sleep with.
all the best,
Susan