I regularly get 14-16 hours before going into the red ( have 120+ apps installed)
Something is running in the background that is killing your battery.
Try doing a phone reset and only add the basic essential apps at first. If the battery life increases, which I am almost sure it will, start adding back your other apps, one or two at a time. Wait a day to see if battery life is okay and if it is, add the next couple of apps and so on.
If that doesn't fix it you have either a hardware problem or a dying battery.
Also, add the wifi and 4g on/off widgets to your home screen. One tap switches them on when you need them and off when you don't. I can easily get over 20 hours that way.
Oh, and buy a 1900 battery - makes a big difference.