You may want to repost this as a tax law question or talk to a tax attorney or CPA as it falls more in that area than labor/employment law.
An attorney-client relationship is NOT created by the answering of this question. If you would like to discuss your matter more fully with my office, please contact me to set up an initial consultation.
Have you filed a tax return reporting self employment income? What does your schedule C say? Do you use accounting software like QuickBooks? If you use QuickBooks, and properly enter income and business expenses you can generate profit an loss statements for any period. Your income is your gross receipts less the cost of goods sold (if any) and other business expenses which could include rent, utilities insurance, office supplies travel expenses vehicle expenses and any reasonable and necessary business expenses. You should not go into a child support hearing without a lawyer.