-Do you mean you have filed the I-485 based on your NIW I-140? If so, you are OK even if your EB1B is denied. But if not, Your status is no more AOS because your NIW PD is not current.
can I apply for a 3-year H1 extension?
-No, because your current status is not H1 and you have used up all the six year h1 duration.