Can I use Regulon without consulting a doctor to postpone the period?

No, you should not use Regulon without talking to your doctor. Regulon contains derivatives of sex hormones, the use of which should be preceded by a full gynecological examination and an interview with the patient, which is aimed at determining possible contraindications. The use of the drug Regulon is fraught with the risk of embolic-thrombotic complications, which can pose a serious threat to health and life. The probability of such an effect is assessed by the doctor, so you should not make your own decision to take the drug to change the expected date of menstruation. I encourage you to consult a gynecologist. In the annex leaflet to the drug Regulon: https://www.gdziepolek.pl/produkty/66459/regulon-tabletki-powlekane/ulotka I also encourage you to watch a short video about hormonal contraception: