Late period

lola

So I was supposed to get my period on the 7th, but I still have not gotten it, for the past few months it was consistent exactly every month. My period is now 5 days late and I am cramping but that’s the only symptom I’m feeling, my breasts aren’t tender they’re just somewhat hard I would say, and my whole stomach has been feeling bubbly. And I’ve never had sex before. So Why could this be?