Trouble introducing hypoallergenic formula

My daughter (7months) was diagnosed with suspected MSPI around 4 months for some small specs of blood and mucus in her stool. I cut dairy and soy from my diet and she’s been having only breastmilk since then. Lately I’m not able to keep up with making enough milk for her so I tried to introduce similac alimentum today. She wanted nothing to do with it. She wouldn’t drink any and just chewed on the bottle nipple. I made a straight formula bottle but now I’m wondering if I should have mixed some breastmilk in. I was fearful that she may not drink it and then the breastmilk would be wasted. I guess my question is— has anyone in this situation had luck getting their baby to drink the hypoallergenic formula by mixing it with breastmilk? I’m wondering if I should try this before buying Nutramigen to try out.