I dated an ER doc for a while here in CO and she had treated a few patients from lower elevation that had altitude sickness. So I asked her once what she usually recommended to prevent this for friends visiting for skiing and that was to drink Gatorade and water both a lot in equal parts to you have your pee the 3 c's clear copious and continuous. So while you may think you drank enough I think what I have seen on hospital walls here in Denver is something like for an average adult male he needs like 64oz of fluid to prevent dehydration. SO start from there and see if you match average or not and adjust.