Ohio father

I am a father to a 6 year old girl from wedlock. We have never gone to court, I have always had my daughter 50% of the time and paid for half of everything I also keep insurance on her. Now her mom is trying to get me for child support. I have decided to go to court and try to get full custody. I would like to know reasonably what to expect, and also can she get me for back child support? Also i was told before we go that we can file a temporary injunction to keep the days how they are for now.