On the shoe thing (and showing my utter ignorance of bellydance): Do you point your toes a lot in your dance classes? My sister was a ballet/pointe dancer up until college, and it made a noticeable difference in her shoe size: pointy toe --> higher arch --> shorter heel-to-toe length --> smaller shoe size. (And no shoes ever had built-up enough arch supports for her). I never had that problem; I do tap rather than ballet.

Or it could just be that it's REALLY FRIGGIN' COLD and your feet have shrunk accordingly. (I've been having to keep a close eye on my suddenly-too-loose wedding ring for just that reason....)