it sounds like the phone is bad.
my 2nd tp will last easy a week with no use at all, but only the radio turned on.
my 1st tp will last about a day with minimal use. with heavy txting or a few hours of talking 2+ it'll die and need to be charged at least twice
so its definitely the phone unless you're using it ALL the time.
my settings are turn off back light after 30 seconds, turn off device after 1 min, i use lumos to automatically adjust my backlight level.
i've switched roms recently and did notice better life with silence 3 rom... but i figured it was because the rom runs leaner... so it doesn't have so many instances running thus draning power
anyhow get another phone and keep the batteries. if you wanna sell the after market ones you bought send me a PM and maybe we can work out a decent price
gl