I laughed when I read this posting--you don't see the irony, do you?

You are stating you shouldn't have to pay because there was no contract, then you state she violated the agreement (i.e. contract) to have only four kids and had, instead, eight. Either there is an agreement, or there isn't. You cannot have it both ways. If you want to state she outlined terms of a specific agreement (i.e. number of kids, amount to be paid, notice necessary, etc.) you cannot expect her to be bound by it while you are not. Understood?

Your not signing a contract is irrelevant since you both understand the terms of the contract ( as evidenced by your outlining the specifics of it here) and you had, at least, a verbal agreement. Verbal agreements are legally binding. Obviously, since your child was there for six months ( as opposed to six days ) you both understood and accepted the terms between you.

She can sue you and I believe she can win. However, if you wish, you can bring a separate cause of action against her if she violated the terms of the contract, but that doesn't give you cause not to pay. But for three weeks worth of child care, you might be better advised to simply move on.