Yep, I know exactly where you are coming form here. I can't take a lot of fluid at all, and when I am absolutely desperate for the loo, I think I only pass about a quarter of the amount the average person does. In all honesty, whilst doing this diet, I just drink what I feel I need to. I never worry about the quantity. So long as I'm peeing regularly, and it's almost clear - so I know I'm well hydrated - and I'm not thirsty, or getting headaches, etc. I just don't worry. We are all individual and the blanket statement of X amount of water isn't going to work for everyone, and I take it more as a guideline and then adapt it to suit me. You are the best judge of how your body is working and if you're comfortable you'll be ok. It's not good for you to be peeing 20 times a night!