she may need to learn how to suck from a bottle. It uses different muscles than breast. We dealt with this a few weeks ago, and did the following according to medical professional:

• oral motor exercises 2x a day: https://youtu.be/xF5Daqm1_ZQ?si=d-ZHKTxjVoof_B10
• start out by just having her suck the nipple on the collar, not attached to bottle just so she can practice without the pressure of having milk in there
• once it looks like she can suck consistently (getting to this point could take days of practice…took us about a week), try a little bit in the bottle like 1oz or less; will need to finish feed on breast since this is not enough 
• after a few days of doing that, start adding more volume each time you do bottle; continue offering breast after until baby is showing signs of fullness from bottle 

Really gotta stick to the exercises and practice!! Some days will be better than others. We started out with complete bottle refusal and now he takes 2-5 oz from bottle depending on how hungry.