A dorm? You accepted a dorm? Is it an apartment on campus or something? The EPIK contract never said anything about a dorm. You should read the contract to them and demand an apartment or villa. If it's some special private or international school that's different.
They never accepted it, they got told they might be moved to a dorm.
How likely is it that I will have to move dorms? (My co-teacher at the girl's middle school, mentioned that I may have to, but I feel like that's unlikely since I'm just changing one school over.)
In the OPs original message "May have to" which means not yet.