Recently I have discovered some things very unusual happenings with my body. My urine has been changing from clear to yellow; I have been suffering from constant thirst; and I have been getting exhausted very easily during P.E. at school.

In order to keep myself hydrated, I have been drinking a possibly dangerous and excessive amount of water (about 7 pints per 24 hours). This has become quite an annoyance at school and I have missed a lot of time during lessons to be excused to drink water. Teachers have been getting frustrated at me because I'm constantly chugging down on water - the PE teachers don't even believe I have it!
The colour of my urine, I have found, follows a pattern - it's clear when I am hydrated but when I go 45 minutes or more without water it goes the ordinary yellow colour again. I read somewhere that the pattern has to do with my kidneys dispersing some three-letter substance and the more I drink, the more it disperses making my urine clear.

So, here are the questions I ask:-
Using the information above, can you tell me if I have diabetes insipidus?
If untreated, how threatening can it be to me?
I am 14 - Will my age effect the amount of water I should drink?
Are there any other liquids that will help me with my dehydration? Milk? Juice?
How will I make the P.E teachers excuse me from the lesson? I get exhausted so easily and exhaustion leads to severe dehydration and the P.E lessons are excruciating.
Is 7 pints of water per 24 hours unhealthy?
Will water intoxication coincide with my dehydration if I continue to drink as much?

Any help is appreciated nonetheless.