I've been backing up for 3 days going into the 4th day, and it is not telling me how much longer I have to wait!

After you cancel the backup, try this and then start another backup.

Go to Settings>Airplane Mode>On in order to disconnect from WiFi. Then restart your phone. After the phone starts up, go to Settings>Airplane Mode>Off. After you are connected to WiFi again, initiate another iCloud backup.

Obviously something went wrong. Cancel the process and start over. When I do a backup, it usually takes less than 1 minute.