I say put your foot down about the sippy cup thing. Your daughter is old enough to start learning that she can't have her way. And throw away the bottles so you don't give in to her. I had to do this with my daughter and she had a FIT! But sometimes if she was FREAKING OUT because she was hungery and NOT interested in the sippy cup, I would feed her something I KNEW she liked like a banana. That would calm her down from a frenzy and THEN she'd take the sippy cup.
What brand are you using? We like the soft spout nuk brand, its similar enough to a bottle that it isn't a total change, yet gets them on the road to the other types.
I agree that 24 oz. is a LOT of milk for a child that age and will deter her from eating food. My pedi recommended weaning her to 12 oz. of milk by 12 months. I have now gone down to 9 oz. as that's about all she wants. We do LOTS of water for the rest of her fluids and she eats LOTS of fruit for vitamins. (my 4 year old nephew drinks tons of milk and juice, and soda if allowed, and doesn't want to eat real food. These drinks are full of calories, mostly simple sugars that quickly turn to fat.)
Also you should be able to give her regular soy milk, we were able to do that at 12 months (we try to be non dairy at home in general, though not for allergy reasons), it saves you a TON of money!
My daughter's typical breakfast is, 1 banana, sm. bunch of grapes, a piece of bread, another whole fruit, 9 oz. soy milk. Sometimes we do leftover vegetables as well. I try to give her exposure to LOTS of different vegetables now so it won't seem strange later on. So far she eats most everything that she can easily chew/swallow, soft things. I always MAKE her try stuff. Usually she likes it after she's FORCED - like putting it in her mouth and not letting her spit it out until its chewed up and swallowed, rubbing her throat helps. ;)
Your child should be able to eat all the fruits, vegetables, beans and grains you can find. If she does have a milk allergy it probably would be a good idea to determine if this is the only one she has.
Bottom line, you help determine the picky-ness of your child. Its certainly not too late to nip this in the bud. But you HAVE to WIN this battle EVERY TIME.
Best Wishes, you can do it!