L.A.
In California a child of 13 is allowed to state a preference that carries weight in court. The judge has final say. You will need to go to Family Court to make everything legal. I suggest you consult a lawyer specializing in family issues. If you cannot afford one, you can obtain assistance for free at the family court. In SJ the aide office is downstairs in the court building on the corner of Park & Almaden Blvd. Best of luck to you.
L.