Bulimia nervosa may accompany anorexia, or it may occur by itself. It is estimated to occur in 1.1 to 4.2% of females. Bulimia nervosa can lead to severe tooth decay, intestinal and kidney problems, muscle cramps, heart problems, ruptured stomach or esophagus, and death.
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I was exactly like you when I was a sophomore. That was my worst year. My family didn't know and I could not tell them. A couple of my friends knew but they couldn't do anything about it either. They just told me to tell my parents. Which I knew would make everything worse. Then I talked to an adult friend I knew, who said I should tell my parents. Of course I said no. So she asked if she could tell them. I sort of agreed, but before she told them my parents figured it out (I'd not been hiding my symptoms very well) and confronted me. It was the hardest moment of my life but I am so much better now. Talk to a teacher, a friend's mom, some adult who you trust. Your parents need to know somehow. I know it's the last thing you want to do but it's the only way to start getting better. Getting better is so difficult but so worth it.