as someone with a bladder the size of a pea nut I have sympathy and actually it is physiologically quite a common experience to need to empty your bladder 20min- hour post a meal/drink etc. My teens have suffered from irregular and heavy periods too and its often been a concern that they could find themselves in a tricky situation if a teacher gets heavy handed. As a parent I also think it is a right not a privilege. If staff monitor who uses the loo and damage problems come to light you can quickly narrow your suspects down.I dont believe in punishing all for the sake of a few. I dont know maybe as parents we'd all feel a bit peeved if it was our child, despite an understanding of the other side.