If the amount of income was more than $400, you must file a tax return to pay self employment taxes. You will qualify for some earned income credit regardless of how low your income, but it may be offset by the self employment tax. You will not qualify for any child tax credit or additional child tax credit unless your net income is at least $3000. Child support and SSI for your child are not taxable and not included on your tax return.
If you have some idea of how much income you had that you didn't keep records on either by looking at bank deposit records or other documents, you can document that and include it as income on your tax return.
When using the online product, you must upgrade to the Self Employed version to get the Schedule C that is required for entering self employment income.
There is another free product called the Freedom Edition that you can use. It has Schedule C. Here is a link to access it: https://ttlc.intuit.com/questions/2026912-how-do-i-switch-to-turbotax-freedom-edition
