Q: MBP charge only when off

Hi, I have a 2011 MBP 13'. I have problem with my MBP as it will not charge when it's on and will only charge when it's off. Once I switch it back on, it will change back to green light and showing that 'battery is not charging'. Even if it charges when the mbp is off, it will take forever to charge. I left it overnight charging and the power only increase like 10-20%. Also, when I use my MBP with my power adapter plugin, the battery will still drain slowly.

I had done the following but none of this work.

Replaced a new battery (Tried 3 different batteries but still no luck. I actually changed to a new battery as I thought there is problem with my old one)

Tried 3 different chargers

Reset PRAM and SMC

Clean my charging port

What else could it be? I didn't really want to send it to the service centre as I'm from Malaysia and there is no Apple Genius Bar here where I could just make appointment and get some advice. So trying my luck here first would be a better choice.

Thank you.