A couple of things. First, you are a great mom! You not only are making the extra effort to make sure your baby gets breastmilk, even though it's in a bottle, you want to give her the added benefit of actually breastfeeding! Wow! Keep at it!
That said, I know a woman who had similar issues with her third child (she had breastfed both her other children for at least two years each, so was an experienced nursing mom). She ended up keeping up with the bottle feeding of breastmilk until her youngest was 1 1/2 or two. So, it can work and be very beneficial, even if you continue what you're doing now.
La Leche League is your best bet for getting to talk to and visit with a human being about this. Google them and you'll find regional info for yourself. You could also look them up in the phone book, check at a hospital or clinic for a local chapter or contact a nearby natural health store.
I suggest you try withholding bottle feeding for a day or two and just offering the breast; express milk right into your baby's mouth and see how she takes to it. Don't go longer than a day or two unless there are very positive and hopeful signs that she will nurse well quickly. Another additional option is to nurse for a designated period of time and give the bottle ONLY after she has nursed for that time. It is much easier for her to get the milk from the bottle than from your breast so, of course, she doesn't want to work harder to get the milk when a bottle is so easy. Make sure you have the best possible bottle nipples that simulate the way milk comes out of the breast and are not too easy for her.
It will take a lot of work, but it IS possible to get her back on the breast. The day or two of nothing but breastfeeding will probably be VERY challenging so get whatever support you can during this time and the whole time you are working on this.
Good luck, peace, and blessings on you and your family.
G.