A few questions to consider (sorry to just jump right in but my little nurser is waiting on me)...
Why does she need to have a bottle? If she's nursing and having plenty of wet and dirty diapers, there's no need to give her a bottle to check how much she's eating.
Is it breastmilk or formula in the bottle? If it's formula, she may just not like it.
How often is it given? If it's a good distance in time (a couple weeks, you said?), she may have simply developed a dislike for it. I know that if I had to choose between my mother's warm skin and the taste of her milk or a rubber thing with formula or breastmilk tainted with the taste of a synthetic material, I'd choose my mama any day.
Now on to the weight charts. If you're looking at the one in the doctor's office, STOP! They're not going to do you any good. Those stupid things are based on male babies who were formula fed in the 70s. For a more accurate source, go to www.kellymom.com and look for the weight charts on that site. There are charts for boys and girls and are based on breastfed babies. And, as long as she is following a curve and is developing normally in every other area, chances are that she is doing just fine. I'm speaking from experience because my daughter and son are both towards the bottom of the growth charts. My daughter was even off of it for a while. At about 3 months or so, she was declared 'failure to thrive' because she completely stopped growing for a few months. But, her other developmental milestones were right on if not early. Now she's doing just fine and the doctor even mentioned her being a little big. So, don't worry about it too much.
And (back to breastfeeding) I encourage you to continue to breastfeed your little one. The time goes by so quickly and she'll soon enough not want it at all. If you can eliminate the bottles, she'll probably be a much happier little girl. I know it's tough and can even be inconvenient, but it's so worth it in the long run. I got to the point that I made it convenient. If we're in a store and my son is hungry, I'll find a chair and feed him, that simple. I am discreet about it and sometimes wear a shawl. But, I'd rather have a happy and full baby than sore breasts and a little one that won't stop screaming.
I pra the Lord gives you peace, guidance and an understanding of what your little girl is going through so that you can help her be a happy little girl once again.
God bless,
A.