Can I get my deposit back?

My case:

My lense is month by month, and I moved out on the third month before the fourth, I informed the landlord one week before I moved out. She told me I should told her one month earlier, I argue with her, that is why i sign month by month lense and pay her $25 per month more due to this, because I don't know how long I can stay there. She scared me it is the law of USA to let the owner know you will leave one month earlier. So she will keep all my $300 deposit, I thought it is really unfair to me. because there is no rule on our lense about telling her one month earlier before we leave. Anyone has any expereince about this, I am ready to sue her. Many thanks for any suggestions.