Chlorella is not especially effective for chelating since it will only remove mercury which happens to be in your digestive tract. You need to get the accumulated mercury out of the places around your body where it's gotten stuck. The mercury will stay forever unless you chelate. The mercury's presence is likely why you are still feeling bad.
I suggest you find out more about the different methods of chelating and choose one you can try. It would likely take 6 months before you feel better though the full act of chelating will probably take longer.
You may already know about this, but here are some words you might search for to find a method of chelating:
Cutler Protocol (DMSA and ALA or ALA by itself)
Cilantro and Chlorella
They all have their good points and bad points; supporters and detractors.
There are other methods too which you can find with a bit of research.
Definitely get that poison out. I can't emphasize enough how important that is.