If you have been given hormonal tablets to treat the ovarian cysts and if you are still taking the same, then your period may not come till the course is finished. If you are not on any medicine as of now, or you have just stopped the same in last 48h, then your period will come in another day or two. If you have not been on any type of hormonal treatment at all, and you are sure that there can be no chance of pregnancy, then this could be a one off delay and is unlikely to recur. The cysts in the ovary may or may not be the reason for the delay, since the ovarian size is apparently normal, and your cycles have been regular till date. Just wait it out if you are not too worried. There are several medicines which can be given to bring on the period. However if this issue becomes recurrent, then should see a gynaecologist.