CAM charges are usually a fixed monthly amount that estimates your portion of what will be due. It is NOT rent. It goes into an escrow account. At the end of each year the landlord should present you with an accounting of the actual CAM charges that were paid on your behalf and either issue you an additional bill or give your a refund.
Your landlord doesn't just get to pick a random amount for CAM just like a mortgage company doesn't get to pick a random amount to keep for your insurance and taxes.
With that being said, if you ask for an actual accounting of the CAM expenses, you may become unhappy. If your landlord doesn't have it together she may discover that you really should be paying a lot more than you are.
It's really up to you how you want to handle it.
If the lease has already been executed by both parties, well, you can just say sorry, it's a done legal document. But I'd start looking for somewhere else to relocate as your relationship may probably deteriorate.
Consider the cost of moving. Signage, tenant improvements, moving expenses, fixture, furnishings, being closed to move....is all of that more or less expensive than what she wants for CAM?
An attorney that specializes in commercial real estate would probably be helpful to you.