Unfortunately, you are incorrect.

Let me try to explain again. You AGREED to a rent reduction. Unless you said, "Ill accept the rent reduction until I move, then you have to start paying again", you are entitled to the rent reduction until you move, and not after that.

You cannot expect ( although you can ask ) her to sign something, but be advised, she doesn't have to. You have the cart after the horse. You should have had a signed agreement BEFORE, but, since you did not, your verbal agreement is the basis. Sadly, your verbal agreements have been unclear and imprecise. If you knew you were moving, perhaps a rent reduction wasn't the best thing to agree to. It would seem she has you over a barrel, so to speak. When she proposed the rent reduction, you had yet another opportunity to identify potential risks to your being repaid ( such as one or both of you moving) so it obviously was unwise to agree to those terms ( unless specific agreement was made to continue paying or revert back to paying cash after you both move.

Bottom line--is what you can prove. Per your own admission, a court hearing would deteriorate into a he said she said--or in this case, a she said, she said case. Ask her to sign a note for the balance. If she does not, taking her to small claims and winning (since you cannot revert back to the first terms of agreement which is more favorable to you, obviously) is very slim.

Good luck.