Am I a legal resident of Arizona?

Two and half years ago, I moved to Tucson, AZ from S Korea with my family. I have U.S. citizenship, AZ driver license (issued in january 2011), my brother own a car registered in AZ, bank account (debit and credit) and live in Apt( moved once, one year each). No history of paying income tax or deduction. just paying other service taxes such as cox or Cell phone. And I'm going to public High school and will graduate soon. When I fill out college or FAFSA application, I encounter with this problem every time. I really need help to determine that I am a legal resident or not.