Don't forget that the phone must have a good Internet connection in addition to ample battery power. If the phone was moved to a location where it does not have a good Internet connection, it cannot update on its location. Also possible that the phone has been powered down.
All that you can do is keep checking every few hours to see if there have been any changes. If nothing has changed at some point you may see a "last known location".
I'm sorry, but realistically the phone is gone, so you need to protect yourself as much as possible.
If your iPhone, iPad, or iPod touch is lost or stolen - Apple Support