What a coincidence!!!
I just had the same problem with battery life.
I called apple and they put me on the phone with some lady who then sent me to support.
Basically they walked me through a process
Save everything on your phone, then wipe everything, and then reinstall some new software.
Took about an hour with the lady over the phone.
They even gave me 15gb in icloud for free!
Phone battery is amazing now
This should help you out big time buddy!