Thanks Jeff. I've contacted my provider.
Mine is kind of a unique case as I run a public arts organization and this is one of our projects. We provide small accounts for artists to represent themselves online. We don't add any fees like a real business might and tend to present the hosting cost as more of a consortium or group effort. And we don't make a profit, rather just make enough from the monthly to pay our bills. That being said, most of the users are at a novice level and are using a very small amount of bandwidth/disk space so it would be cool if we could pack more people in without paying more. But yeah, it depends on what my provider says. Regardless of how low the usage is and how small this project is, I wouldn't want to get shut off.