Recent research articles about drinking water say that the "drink x amount of water a day" concept is being overstated. Water consumption should be more based on thirst. Pushing water can be a strain on the kidneys and other systems. Maybe she needs to consume less in the afternoon and evening.

Anxiety can also cause a focus on various sensations. I cannot go to sleep with any level of bladder sensation. I could understand how this could impact her, especially as the dark part of the day approaches and her anxiety levels rise. Has anybody suggested CBT, Cognitive Behavioral Therapy, for her ? I don't know if it is effective with somebody as young as her.

More questions to consider. I know you are already at overload.

My best to you.