title_body: How to sync my Kindle with my Kindle library without using WiFi?
upvoted_answer: Using Calibre you could try :
  
  
  Adding the book in the Calibre library
  Sending the book to your Amazon email address (Right click on the book > Connect / Share)
  Sending the book to your Kindle while it is connected to your computer (Right click on the book > Send to device)
  
  
  Of course this requires some initial configuration (telling Calibre how to send email, ...) and I can not guarantee it will work having no 3G Kindle to test it myself.
  
  But it seems to be worth a try as it would most likely make sure that the file that gets copied on your kindle has the right format/information to be identified correctly.