If you had iCloud set up you could have tracked your device since you turned off the device you can't track it unless it's on wifi. You could have also remotely lock the device and put a lock on the device, and/or wipe the criticle data.
Sorry, unless there is an investigation into a high level crime in which the phone is necessary to track a missing person, et cetera if you shut the phone off there is nothing that can be done. If it was actually stolen the MEID/ESN will show up if someone tries to activate it. If that has not happened then I am quite sure it was not stolen. Unless the person who stole it has either a). not powered it on to use or b). has not sold it to someone who has yet to try and activate and use it. If you believe it is either A or B and you believe it was stolen the MEID/ESN will be flagged as what many people looking to buy used phones want to make sure the ESN is "clean" [i.e. not stolen]. Someone buying a unclean ESN is certainly an idiot.