Your agreement with her was obviously not legal so she cannot enforce it. However she certainly can report you to the IRS and CIS if your employment was not authorized.
The above is intended only as general information, and does not constitute legal advice. You must speak with an attorney to discuss your individual case.
I agree with my colleague. There is nothing that would prevent her from reporting your employment (even under whatever number you already provided) to the IRS or immigration authorities. Also, you may want to check with a tax professional to understand whether you need to declare your income and/or file income tax. Your "A number" doesn't expire.
This answer provides only general information and may not be relied on as legal advice. For more information about immigration law and policy, please visit www.lichterimmigration.com or follow us on twitter (@lauralichter) or facebook, www.facebook/lichterimmigration. To find an immigration lawyer in your area, log on to www.ailalawyer.com. Listed attorneys have been members of the American Immigration Lawyers Association, the nation's premier bar association for immigration lawyers, for at least two years, comply with annual continuing legal education (CLE) requirements and carry malpractice insurance.