I would recommend that you drink only to thirst, not a gallon per day which is probably double or even triple the amount your body demands and would thrive on. The excess water is causing your body only to work harder and is not providing any benefit. Also, avoidance of the excess water alone can contribute to a settled stomach, though it is certainly possible to encounter some nausia even when drinking only to thirst.
Drinking water-only and no lemon juice or salt is also strongly recommended since anything but water sends mixed signals to your body and interferes with the fasting process, standing in the way of allowing the best possible results to be achieved.
Lastly, 30 days is generally considered to be a fairly safe long fast, but 60 days is a very long time to fast without supervision. From your words i discern that body fat is not an issue, but it is also possible to run low on one or more minerals or vitamins. At minimum it would be a good safety precaution to monitor your blood pressure and heart rate every morning where according to chrisb1, any dramatic fluctuation from day to day serves as a warning sign that the fast should be broken.