K.K.
My difficult-to-take a bottle son eventually ended up using a NAM nipple on an Avent bottle (basically b/c I had the bottle and only bought the nipple; the avent ring fit). They are sort of flat.
One thing I WOULD NOT suggest are the Adiri or any of those bottles that are supposed to look like a boob, or collapse like a boob, etc. They are so messy, they leak and bottom line, they still have a silicone nipple that doesn't feel like mom's.
I have 4 kids, all BF, but in a pinch they need to know how to take a bottle. Keep trying, have dad do it, and I think if she is hungry enough she will eventually get the hang of it!
Good luck!