You have to be 18 in Ohio to "decide" where you want to live. However if your mother files for modification of parental rights, you will likely be afforded the opportunity to speak to a guardian as litem or perhaps even the court itself. Courts will often consider the wishes of children who are mature enough to articulate good reasons why they want what they want. Getting good grades and being a good citizen will add to your credibility. You might also consider keeping a secret journal of what your father or stepmother does that you find bothersome. This documentation may help a guardian as litem understand your situation better.
This answer is provided for general purposes only. If you need legal assistance you should consult with an attorney. If you wish to discuss the facts of your case with me, please feel free to contact my office via the information below. Please note that neither my response to your question nor your contacting of my office creates an attorney-client relationship.
Tamms Law Office, LLC
6457 Reflections Drive; Dublin, Ohio 43017