[ld5596]

-I have tried different chargers
-I have bought a new battery(terrible waste of money)
-I have cleared Dalvik cache
-I have turned on 'Low Battery Dump"

I have installed Galaxy Charging Current, and it gives me 100mA almost all the time (Reference: 999mA).
I adjust or remove the charger and plug it in again, it shows 500mA or so. Its basically 200mA on an average and becomes 100mA very easily. 100mA btw is when it isn't charging at all, I never see an increase in battery percentage. I charge my phone the enitre night only to 'increase' it from 3% to 3%!

The battery problem exists for different custom roms, and after wiping cache and even after factory reset. Its really moody, its 1000mA when I am really lucky, for its entire charge.

HELP!!

[B. Diddy]

One remaining possibility is that the charging port is faulty, or perhaps has a loose connection.

[ld5596]

And what do I do to get that fixed?
Or is it not in my hands at all?

[hallux]

It might be cheaper or a better use of money to replace the device. You can get some Motorola devices that will be better than that 5 year-old device. You can get a Motorola Moto G4+ with 64 GB of storage for $220.

[B. Diddy]

And what do I do to get that fixed?
Or is it not in my hands at all?

If you're good with repairs, you could probably find a YouTube video showing how to replace the port yourself. But if it were me, I'd take it to a repair shop. Or, as @hallux said, trade up for a newer and better phone.