What do I need to do??

I am 16. My mom lives in oklahoma and My dad lives in Tennessee. I am in Tennessee atm but i'm living with my gma but I wanna go back to my Moms. I lived with my dad from when I was 3-11 and was stuck in my room or outside. I went to my moms and i've been somewhat back and forth. Well my Dad wants to stop me from going back. They have joint custody dad has primary and Mom has secondary. Can he stop me and what do I need to do to find out how I can go back? I mean I don't even live with him. I can't stand my Dad or stepmom. Please help! Should I talk to a lawyer, DHS or what? Thankss!