You are a little on the underweight side... this could affect your menstrual cycle.

Are you sexually active? If not, I personally would try to avoid birth control pills (side effects), but your physician will be abe to help you more with that.

When you say you are irregular, do you mean that it just hasn't been coming every 28 days? Because some people have slower cycles, and it isn't unusual for a girl your age to have periods every 6 weeks, for example, instead of every 4.

Also, are you an athlete? They commonly have irregular cycles.

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