How can I get my child custody order modified?

I am a military wife and my daughter who is 12 years old, has maintained her desires to live with myself and my husband. We are getting ready to move again and my daughter wants to move with us. My case is difficult to explain because my ex husband NEVER should have received physical custody! Once the trial was over, I received a lot of information stating that my ex inlaws were originally good friends with the judge and with my ex's attorney. Their attorney steam rolled me, even though he had a documented history of violence toward me. My daughter had just turned 6 years old! She was already living with myself and my current husband majority of the time. I had a stable life with stable income, health insurance, and most important, my time. I was not going to have to work. Her father at the time was single, unemployed, no insurance, no steady income, living in his parents home, he was unstable. How did this even happen? This was almost 7 years ago. I still fight for her.