Hi Becky,
I was in the exact same situation, but a little earlier than you. Good on you for BF for these months.
I really don't think you should stress about it. LOs really know when it's enough and she won't eat if she doesn't want to. However, you should read her signs while she is taking the bottle - if she is "playing" with the bottle, shaking her head, kicking her legs - then she doesn't want to eat anymore. If she is happy, I'd say she is just hungry.
You could always take her to check her weight and see if it's all alright.