What does it mean if start to get my period twice a month?

Hormones not right: Not uncommon at your age but you need an exam blood work and ultrasound and maybe the endometrial tissue sampled to r/o problems , if everything is ok and u are tired of getting your period which is worthless at your age I do endometrial ablations in my office where we get rid of the endometrial tissue with a simple 8 minute procedure and no more worthless bleeding and cramps.