I'm worried about my teddy bear hamster, not sure why she does this..?

To be honest, it sounds like your hamster is stressed. I am surprised at this point that she is showing no signs of wet tail. If you don't move her cage soon, she may develop wet tail. I strongly suggest that you have a chat with this roommate of yours, and find a new place for your cage. You should buy some wet tail medicine just in case you notice any signs. Once the stress of the cat goes away, your little friend should be back to normal. I hope your hammie is okay!