When the parties split the time 50:50 the court considers that parent with the lesser income as the custodial parent and directs payment of child support from the parent with the larger income to the custodial parent. In your case you say you have equal incomes and you have the children for the bulk of the time. For the purposes of child support you should be considered as the custodial parent and you should be receiving child support from the mother.
The only way you can change the Order of Support is to file a modifcation peition and a child support petition against your ex. On the modification peititon you will need to show that since the entry of the last order that your circumstances have changed and that your order should be lowered or that there should be an order of support for her to pay to you. If the time that you have the children has increased since you got the support order, that should be grounds to file to seek to modify your Order of Support. If your current parenting time situation was in place when your got your support order it is less likely that they court will modify your order than if your parenting time has increased. You should allege that you are the primary custodian since you have the children over 2/3 of the time and therefore you are entitled to receive child support from the mother.You also should allege that the amount you pay has limited your ability to provide for your children when they are with you.
I would urge you to consult with counsel who is familiar with the Jefferson(?) County Family Court and have them prepare your peititon(s) and represent you in court. I understand that you have financial problems but if you end up receiving support rather than paying it it will have a long term benefit to your finances.