I used to take 600/600/1200mg a day for neuropathy and paresthesias, but many people with MS take it in higher doses. I'm not aware of any ceiling for it.

Right now I'm taking 700mg off-lable for psych as a mood stabilizer, but I usually lower my dose if my mood is low, and raise it if my mood is too high.

I'm sorry you're so depressed, Mari
I hope that your pdoc agrees to increase it, and it helps. I think you should be able to adjust to the sedation given enough time