Can being in a dry place (low humidity) increase fluid loss even if youre not hot/sweating (skin is dry)? when a/c is on, i always get thirstier!

Yes: You inhale air with humidity (5-75%) & exhale (~100%). You create more water deficit in dry envts than humid. You also lose through your skin. Sweating is more prominent in humid envts as a matter of physics. Homes in dry areas have inside humidity similar to outside unless a humidifier is used. Your drinking pattern is more likely due to access rather than need.

Agree with Dr. F: Drink enough water daily so that your urine is mostly colorless. Have a healthy diet, exercise 30 minutes/day, drink plenty of water, have safe sex, no tobacco alcohol weed or street drugs. For nutrition: http://www.choosemyplate.gov/.