Travel Back
Marusenka,
It seems to me that you are very close to receive your GC, probably a little more than 1 year.
On the other hand, travelling to your home country can be risky to your status.
As far as I know, you don't need an advance parole, what you need is a RTD, and when you come back, you have to demostrate compelling reasons, showing why you travelled to your country. It will be at INS officer's discretion to let you in.
I understand that you have been waiting for a long time, and sometimes you have to make decisions.
Let us know your decision and the results.
Good Luck!!!!