Because your current regime is a dilution technique gone completely out of control. For starters, drinking fluids days before the U/A is useless. It may make you urinate frequently, but it has no effect on the rate in which THCA is filtered from the bloodstream by the kidneys. Drinking fluids is only good for the day of the U/A.
Drinking gallons of fluids on the day of the U/A will increase the chances of the sample being deemed "overdiluted". For the proper way to dilute, follow the steps outlined in the Dilution sticky thread.

Detox drinks are a scam. Their makers and peddlers exist only to seperate the credulous from their hard-earned cash. You can spend upwards of $200 for a magic elixir and accomplish nothing different than you would accomplish with just vitamin B2 and water.

Forget the magic detox potions and drowning yourself with gallons of fluids and just follow the Dilution sticky thread.