Well, the situation has been rectified, after some nastiness and a lot of consulting my school's Residential Life and Greek Life offices. Basically, it turned out that my sisters did not "understand" my situation, and were just thinking that I did not want to live in the house.
After I had to personally explain it to a few of them, they understood, but I'm sure there are going to be some hard feelings. Oh well. I was dedicated and committed to the house last year, and I can be this semester.
Bottom line: just because you don't live in the house (ahem, dorm), it doesn't mean that you aren't dedicated to the sorority. I know that I'm just as active, if not more than, some of the in-house members.