I think you need to keep the lines of communication more open than you have been. When your daughter finished the month's homework in one night did you talk to the teacher about it?
But, I think you're fighting an uphill battle without testing to figure out exactly where she is, what she knows and what she needs to learn. I would go to the meeting and ask for above grade level or achievement testing. Without it they're probably trying to give her 1st grade work, which is just as inappropriate as the stuff they're doing in class.
In advance of the meeting I'd practice some effective communication techniques, too. Things like active listening and ways to make sure they know you hear and value their concerns, and practice presenting your own thoughts in short, clear paragraphs. Don't get dragged down by anecdotes or extra background information that's not needed to understand what you're trying to say.
In the meantime, I'd purchase a homeschool math curriculum and start working with her formally.
