I am feeling dehydrated, too, and I am not nursing right now. I can only imagine what it's like for you. I have a hard time because when I try to really increase my water intake during the day, then I have to get up to pee three or four times at night. But maybe if you are nursing, that isn't such a problem since you're up anyway.
I think you're doing the right thing to keep the water by the bed and drink it when you can. I would just drink water, herbal tea, whatever, at every turn during the day and also really decrease diuretics (sp?) like caffeine, cammomile, etc. You are probably already doing that.
I am with you with the nausea. I too am having it all day, combined with incessant hunger, which isn't really a great combination. I suspect many of us are in this situation right now. I find that red raspberry leaf tea helps me, more than ginger at this point. I have cup in the morning with my breakfast and I think it helps.
I hope you find some relief from both afflictions soon!