Suggest Remedy For Delay In Periods

Hello Doctor I haven't got my periods over twelve days now. I should have ideally got them by Jan 20th. I got my cycle before that on 20th December. I haven't really had any sex after dec. In the months of Nov, may be my boyfriend rubbed his penis on my vagina, but I wasn't naked. I had my underwear on. I'm just a little concerned as to why I haven't got my periods this month.