To user Small White Car: Notes are definitely included in the backup, at least in iOS 6.1. Yesterday, my iPhone 5 was replaced because of a defective camera. When I did "Restore from backup" onto my new iPhone, all of my notes magically appeared.
You could try restoring from backup again.
The backup itself is located here:
~/Library/Application Support/MobileSync/Backup/
However, everything has incomprehensible hexadecimal names, so I don't know how to find just the notes. Maybe you could try searching that folder for some text that you remember was in a note?