Computing CS based on salaried w/benefits vs W-2 wages

My ex and I separated in March 2005 and were divorced in Sept 2006. She filed a motion for back child support in Sept 09 and I was told that she can go back three years. We had and currently have 50/50 custody since separation. Currently our salaries are the same so the worksheet shows no one owes either.
The problem is between September 2006 through September 2008 I was making over 25k a year more then she was and this is what she wants back child support on. During this time I was a W-2 contractor so while I made a nice hourly rate, I had no vacation, no benefits, no work subsidized health insurance, no 401k contributions, nothing but my hourly rate. My ex on the other hand, while having a lower salary also had 5+ weeks of vacation, 401k matching of up to 500 a month and only had to pay a fraction of what I was paying for health insurance since it was company subsidized.
Do any of these factors weigh into determining each parent’s salary for Child support? When all benefits are included the gap between our salaries are significantly reduced. To me, her five weeks of vacation and 401k employer contribution should count for other income at the least; otherwise the court is comparing apples to oranges.
Thank you

No child support only considers the gross income of each party, 401(k) matching and vacation time are not accounted for in the calculation.