I know exactly what you are saying - Our DS would drink his water and juice out of a bottle when he was teething, but still refused his formula. I think it is cause the formula is a lot thicker, and they have to suck harder to get it out. That is my guess.
When our DS was refusing his bottles, we used to give him a dreamfeed when he was asleep, just to get those extra calories in him.
How is she with her cereal? You could try getting extra formula in there, and perhaps offering her cereal twice a day, to get those extra oz in.
I know how hard and worrying it can be, but all I can suggest is just keep on offering it to her at your usual times, and she will eventually start taking it again.
Sending you loads of hugs.
Keep us posted on how you get on.
Paula x