Do I say I supported myself if I lived off earned income + student loans? My parents co-signed, but I have not received aid from them and I will be paying the loans off

This might be a conversation to have with your parents. They may have provided other items in supporting you and plan to claim you. See IRS Worksheet for Determining Support.

Q. Do I say I supported myself if I lived off earned income + student loans, my parents co-signed?

A. No. For purposes of the tax dependent  support calculation, co-signed student loans are counted as support provided by the parents. Who is going to pay them off does not change that.