If you carefully read your lease I'm sure there is a clause stating that it is her right to ask you to leave the property whenever she pleases. What she CAN'T do is take your money for time you haven't lived there. If you move out early, you need to be refunded the pro-rated amount of rent. Really, your rent should have been pro-rated for moving in a day late.

Go through your lease VERY CAREFULLY. There has to be a clause about early or late move-in/out. If not, then you are the one with the loophole and the advantage.