I am not a fasting expert, but 64 oz of water a day isn't much unless you weigh under 128 lbs..
Half your body weight in ounces is a good estimate of healthy daily water intake.
If your body is saying it's thirsty, I'd honor that thirst by giving it all the water it wants.. If your system starts feeling "wrong" or you feel you should end the fast, I'd end it.
Keep listening to your body, follow your intuition..