Do you not feel hungry? Buy lunch at school. Buy breakfast at school too if you have time. It doesn’t have to be much, just something to give you some energy and maybe some protein. Are you not tired? You’re not going to function well only getting one or two hours of sleep per night. That means you won’t run as well, you won’t do your homework as well or as quickly, etc. In summary, listen to your body’s needs. When you feel hungry, eat. When you feel tired, sleep.