So... update! I had to go back on high doses of chlorella during fasting. Emotional symptoms and rage came on very heavy around 21 days, so the chlorella was necessary to remove the mercury while fasting and keep my emotions stable. I fasted for 73 days total and only decided to stop after becoming pregnant and some personal family things happening meaning I was going without sleep and having to exert myself a lot. I began to feel sick and weak from it and decided (primarily because I was pregnant) that I would stop fasting.
By the end of the fast, my tongue was normal size, my tooth grinding & clenching completely stopped, I could eat any of the sulphur foods without anaphalactic response, my hand and foot neuropothy symptoms completely stopped, my swollen lymph nodes were smaller, but still slightly swollen (have been since about 10 years old after dentist put in like 12 Amalgam fillings in just a couple months), etc.
My conclusion: Water Fasting to detox mercury is very safe if you stay on a high dose of an effective binder (like chlorella - which means technically it is not a pure water fast, but still getting the benefits). I wanted to share this as I had a hard time finding information about this online. If I had not gotten pregnant, I probably would have continued fasting for 120 or more days to clean out as much mercury as possible.