Security Deposits

The person who sublet the apartment that I loved into is not the landlord. She wrote up some kind of a contract. I was mislead to believe my stay would be for a longer period of stay. She collected a 900$ security deposit from me. I moved in December 1st and she collected 1800+$ that day and 900+$ before December 26th. Shortly after she told me I have to be out on February 1st. I have done nothing wrong of that I am aware. When I had asked her why, she told me”It’s nothing against you I just need the space.” A week or so after she asked if she could show my room. Now when I reviewed the contract it stated that 30 days after leaving I would receive the security deposit. I don’t trust this situation. I wNt to know whether or not I am entitled to stay for the month of February or if not that I receive my security deposit back on the day I vacate