This should be based upon his known strengths. Second, and more important, is that you must teach him to please himself and not others. This just represents dilute urine. As long as he is otherwise healthy and represents good hydration then I wouldn't be worried. If he is showing signs of excessive urination or seems extremely thirsty, then you should check with your pediatrician.
Girls can certainly ovulate for quite some time prior to beginning their menstrual cycles.
I would consult with your pediatrician. This is to make sure that her uterus is normal and that the pathway for menstrual flow is open. A complete physical exam and perhaps a pelvic ultrasound can answer this question. Here are a few things you may not have tried. Leave on over night and then shampoo.