Rule #1: You shouldn't chelate when the source of mercury (amalgam fillings) is still present, it will make you worse.
Cilantro and chlorella are definitely chelators and you're lucky you don't feel worse. Also, if you're going to use them, you need to use them with a raw fat (like a raw egg) or the mercury will just redistribute around your body.
Personally, I recommend Cutler's methods of chelation and will be using DMSA and then a DMSA/ALA combo in a few months down the road.
I had my Amalgam fillings out 2 months ago. There is no rush to chelate at this point, my body is already dumping a tonne of mercury without using chelators removing additional mercury from my soft tissues.