Child custody

Three years ago I went to pretrial with my baby's father. We agreed to joint custody and child support. Our scheduled flip flopped according to his work schdule a lot but time was split between us 70/30. His lawyer wrote it in papers to have joint, shared, equal physical cusotdy even though we agreed otherwise. I didn't sign but ended up agreeing due to fact that he was withholding child support and I had no more money to fight him in court. Over the years we have constantly fought and went back and forth with splitting time because our judgement was so vague. He recently filed and brought me back to court because he wanted me weekend to take our daughter to his wedding and he wanted to claim taxes every year. I wanted to push to modify custody but since there was no matieral chane in circumstance they wouldn't allow it. I felt I was forced into agreeing to giving him taxes as well as keeping child support same but he did add our daughter on his insurance after I've been paying it for almost three years now. My concern is when we go back to court to modify custody because she will start school in august, will judge allow me to move cusotdy from shared I joint since the flip flopping has not worked for us. I want to keep time split 70/30 with him getting her 2 nights and week and every other weekend. I don't feel we should keep r shared and co-domicile parents. I want to switch to joint with time set as visitation and me be domicile parent. We can't agree and argue and it a lot do back and forth with a young child just starting school. He's a good dad but our inability to get along is taking a toll on my daughter. I want to set a my strict schedule that will allow her stability when she starts school. How likely will judge be to grant this?