My period has always been irregular. for example every 3 months lasting 7 days and i haven't had one for 4 months now, should i go see a doctor?

Metrorrhagia: Metrorrhagia, or periods that occur at irregular intervals but usually in between the normal cycle is a common problem among young females. Is it possible you could be pregnant? Regardless, there are some easily treatable causes of abnormal uterine bleeding, you should definitely see a women`s doctor.

Yep: It could be a few different things. See your doc. They can help you figure out a treatment plan.