Help!What is my current status?

Right now I have a big problem about my current status. Since I transferred to another degree program this semester, my school required me to apply for a new I-20. They said that the new I-20 will maintain my F-1 status. They said if I don't have a new I-20, they will report to the Immigration Department and say that I violate the immigration law. What should I do? Am I supposed to be AOS after summitting I-485 application, which means that I don't have F-1 status any more? I am so confused!