I have been working without a Permit?

So I got a job over the summer where you can't really file for a work permit because it's not during the school year. I'm 16 and I have been working at my job for 3 months now. On my application It says 3 other places I've worked at, but all were under the table (my father, family friend's businesses etc.).

I suppose my manager assumed I have a work permit because of my prior experience. I planned on getting one once school started but It didn't occur to me since I was already working.

Can me and my manager get in trouble event though its only been a few months? Is it too late to file for one without getting penalized or something. Should I just wait until I'm 18? Or should I just not worry and ignore it.