Is your daughter overweight? Fat affects how hormones are metabolized and stored in the body. There are so many things out there with natural and synthetic estrogen mimics. Hormones in milk, milk products, meat, soy and soy by products are the main culprits. All of this is hidden in our packaged processed foods.
My recommendation is to only buy organic or hormone free dairy. Stay away from processed foods as much as possible (I know, sometimes life gets in the way!). Call your doctor to see if there is some underlying medical issue. This just may be normal for her.
Buy as close to the actual food product as possible. Whole grains over white flower or white rice, that sort of thing.
Good Luck!