PERM granted, then what?

I got mail that my PERM is granted.
As the gc process is so slow, I considered to go back school for a PhD, and then may go back China. I am not happy for what I am doing, and do not feel stable in the company too. I heard that I can not apply F1 if I fill I140, is it correct? I am a part-time PhD student now holding H1.

Any suggestion what I should do next ? stop the gc process and just wait whatever will happen in the future.

Thanks advance for your suggestions.