Then tell your teacher, she'll assist you in getting the help you need. Hopefully, you haven't caused yourself any severe damage internally. Erosion of your esophagus, erosion of the enamel on your teeth....etc! Get help before it's to late!
please tell someone... I'm 23 and had bulimia since i was 12 years old.. If you think its bad now.. Wait till your older it will be much worse