Has been eating cereal for years in Breakfast.

I'm 14. I've been eating cereal for breakfast on school days for as long as I can remember. The only thing I eat before going to school is cereal. I've only ever eaten cereal. The earliest I remember eating it was in 3rd and that's all. I only rarely eat something else for breakfast on days when I'm sick and can't eat milk. I eat other stuff on weekends, but I only eat cereal on school days. What are the potential health risks that I've done to myself by doing this.