Initial few periods after menarche
are most of the times irregular. This irregularity will settle with time (mostly in 2-3years). The only precaution you have to take is not to put on weight as obesity might compound problem & prevent regular ovulation. Right now you need not take any medicine if irregularity is not troubling you. Apart from OC pills, you can take progesterone
to regularize periods, but most of times its not necessary.
Wish you good health.