Hi and welcome to the BW website.
I would pick one time of the day when your lo has a feed, and continue to just offer the bottle. Perhaps try this when your lo is at her hungriest. I would not force the issue, if your lo refuses the bottle give her a few minutes break and offer again. Have you tried offering expressed breast milk in the bottle first to see if your lo will take this? If your lo takes the breastmilk, you could then slowly introduce the formula by mixing breast milk and formula, and then upping the amounts of formula until your lo is fully on formula for this particular feed.
It sounds like your lo is using the breast to fall back asleep again. This is a prop, and your lo needs the breast to fall asleep. Try posting on the props boards, and the ladies over there will be able to help you wean yourself from being a prop.
What does your EASY look like during the day, can you post it so that we can have a look.
E
A - how long
S - how long - does your lo fall asleep independantly or does she need to be fed to sleep?