F1 in the process of GC application, Can I work without EAD?

I am in the process of I-485. Before filing I-485, I was a F-1 student. I am still a student, not quite sure about my status. Just heard from someone that I was not supposed to work until I got my EAD. actually there were about 3 month between I filed my application and I got EAD. My question is, was it ok for me to work in that 3 month? I did not think it was a problem, since I was in a degree program, it was required to do RA.