Hi,
You're right, BC pills are used frequently by dermatologists and gynecologists to control hormonal disorders in women, and acne is just one of them. However, taking ANY medication (other than the usual pain killers or other OTC drugs) by yourself without consulting a doctor first is foolhardy, esp those that work with hormones such as BC pills, and more so, when you're in your teens.
A doctor will be able to determine if you are indeed the right candidate for BC pills to control acne or for your periods. Do not start them all by yourself for these reasons, it may backfire. Please consult a gynecologist for your periods and dermatologist for your skin. all the best.