Sounds to me like she's getting greedy and you might need to put things into writing. I hope you can sort it all out. Maybe if you're not 100% happy with her, look into council run Family Day care?
We have been looking at FDC. DD1 started with a FDC but when DD2 came along it was so much harder to get a placement for 2 of them. Hence why this arrangement was working for us.