I’m struggling with the switch to whole milk!

My daughter is such a good eater when it comes to food but she will not drink the whole milk. She literally gags when I try. We cut out bottles completely and she wouldn’t even drink her formula so we brought the bottle back and thought too much change at once. So I’m trying the wean approach. I mixed 5 ounce of formula with 2 ounces of milk and she drank it fine in the am. Then she had regular food all day. But then I tried again with the new mix she refused and would spit it out. So frustrating and I’m worried that she will get dehydrated. She drinks water just fine throughout the day from a sippy cup. I think another week of trying and then I’ll have to contact her doctor. Ugh any one else having troubles!?