So, I did finally break down and ask my nearest desk neighbor about the trash bags. It's no wonder I was confused. Evidently new bags are supposed to be put out for everyone by sanitation staff every week, but they never are. Sanitation folk are fickle beings, I suppose. Anyone needing more bags has to go and consult the trash bag guru, whose job has nothing to do with trash but his office is being used to store the extra bags for some mysterious reason.
Considering that I don't even know this person, I don't anticipate consulting the trash bag guru anytime soon. I think I'll just try to make my remaining bags last another month or so, and hopefully the coming spring thaw with warm the hearts of the sanitation folk enough that they'll take pity on us, the humble cube-dwellers, and share their bounty of refuse-catching receptacle liners. Here's hoping.
Peace and love, readers.