How did you fill in the answer for the question "have you filed for permanent residency?" did you say no? I don't have real life experience with this kind of case, but to keep GC and application for GC, I was cautioned by my lawyer NOT to make mistakes in tax return. I would suggest you to talk to your lawyer to see what exactly should be done for your case. If any good news, please keep people in the forum posted for all the good.
Good Luck