With 6 hours use and 13 hours standby You may want to test again. What things have you fine tuned, notifications, system services, what was screen brightness? Also signal strength make a huge difference. The same phone in if fervent location may drive the radio very hard trying to reach cell site or wifi router. If you are close to Apple Store you can have them check your phone's battery. But if in other respects, screen, buttons, etc you are happy I would tend to keep it.
What to turn on and off on location system services?