What do I do if i haven't registered at the police station?

I've got an apartment for a month in Shanghai and i was at first going to stay for 2 weeks because it was too fa from my work place and the person who sold me the apartment told me that i don't need to register cause i'll be here for only 2 weeks. But then I signed the contract cause i couldn't find a place close to work and when i went the register at the station the lady told me that i didnt have proper documents. There goes another week and and the girl never gave me the last paper for the document and now its 3 weeks and i'll be leaving in a week. So my question is that would i be fined for not registering at my first apartment but I will be registering at the other place.