If the gross income is 20k, is OP saying all that came from apt cleaning, no taxes were filed? Or truly “on the side,” as in a little extra toward groceries?
One small bit of background. https://www.freelancersunion.org/blog/2015/02/10/got-side-hustle-heres-how-pay-your-taxes/ OP won’t have a 1099.
OP needs to go back to the finaid app requirements for his colleges. They’ll ask for a copy of the tax return or a solid explanation if there isn’t one (if they allow that.)
Beyond that, we don’t know enough.