Divorce Support Forums: Child support

I have a question about child support. Me and ex have joint custody and we have the kids the same amount of the time. I pay all daycare costs and after school costs. I have them monday through friday. I make about 50,000 a year gross and she just started working. It has been two years since our divorce. I was averaging 200 a week in child care and I pay the insurance. I pay 500 a month in child support. I have never thought this was fair since the divorce. My question is is we come to a agreement how do we make it official? Also has anyone ever heard of child support being paid by the parent that has the kids the most? I have the kids alot on the weekends when she works and when she cant get them. I also take the kids to her and pick them up so she can see them. Any help would be appreciated.