Oh, Rachie!
Keep in mind that breast cancer has a high survival rate, and that positive thinking and prayer (which I wholeheartedly send to you and your mother) can be very very helpful and healthful.
I can see how you would turn to food to help you cope, but don't why don't you call your mom and see how she is doing, talk to a friend about how you are feeling, see a counselor at school, or even post to your friends here.
I know that this is a difficult time for you and your mother. But hang in there sweetie.