You are a GA resident until you proactively change. Just going to school in MS does make you a MS resident, even if you live off campus. If you are still a dependent, on your parent's tax return, you are considered to be living at their resilience.
Typically, you must get a MS drivers license and car registration and register to vote. Your intent not to return to GA is a factor, but not enough in itself.
You should file a MS non-resident return and a GA resident return. GA will give you a credit or partial credit for what you paid MS
