Default Battery Problems

I'm using a Nexus 5, its my first Android device, and so my first time rooting.
I rooted yesterday using the Android SDK, and installed TWRP.
The root worked perfectly, and I have tested it. All I have done since rooting (unlocked boot loader at the same time, so I'm clean on stock), is install a few Play Apps like Twitter, WhatsApp and then BusyBox and dSploit.
I haven't added any customisations or anything, and my battery is now awful!
i.imgur/AkdAKjW.jpg (Can't post links yet)

My screen has been on for 50 minutes...

I have brightness on the lowest setting, have turned off vibrate on touch, turned off Wi-Fi, turned off Location, set to use 3G not 4G, set display to turn off after 15 seconds...

Im sure it can't be anything to do with the root, but I don't really know too much about it. Is there a problem with 4.4.2 and battery life?

What else can I do to improve it?

Ideally I'd like to be able to have a max of 3-4 hours screen time, and the device to last for 14-15 hours.

I was easily getting 14 hours before I rooted/updated, but now my battery life has just screwed up.

Why is the OS using up so much?