I-90 priority by state?

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Me and my sister e-filed our I-90's at the same time since our GC's are expiring in October this year. Our receipt date was mid June this year. It's already September and we only have the receipt notice and nothing else since then. As of this posting, Vermont's I-190 status is March 8, 2006. I'm getting worried that my GC will expire even before they even get to me. Would there be a problem anywhere that I need to be worried about when this happens (I have a pending N-400 though, if that matters in this case)?. Plus I have a planned trip outside the country in December and I'm worrying if I can still be able to travel.

My sister's employer had already mentioned this to her since she will be terminated when her GC expires. I told her just to show the I-797 as proof that she has her replacement card application pending since she's getting worried as well.

Another thing that's worrying me is that my sister's friends who lives in DC and VA (we live in MD), e-filed later than we did and they already received their biometrics appointments. As far as I know, applicants from DC and VA both send their applications to the Vermont Service Center. What gives?