Lia0274,
Yes I agree with doctor1. It's still not too late. You can apply for your AP (I-131) even at this stage. It won't cost you a penny. It's all included in that I-485 fees which was $1010. Just include a copy of I-485 receipt shwoing you have paid USCIS $1010. If your GC is delayed for some reason, atleast you will have your advance parole for travel purpose.
Keep in mind I-131 document is not for everyone. If you ever overstayed your visa for more than 180 days, you would probably be denied entry even on I-131 document. In that cases, GC is the only document you should be using. Double check with an attorney to be more sure.