Period

Want to ask a question I have my period September 27th I got off October 5th 6th I had sex on the 9th then I had sex again on the 16th when I went to wipe myself it was a light light pinkish red but real little I've been cramping for about maybe a week and a half real bad the bottom of my stomach my size got short pains and my lower back have cramps what could that be I'm in regular periods so I don't know if it's supposed to come up October 27th my period it didn't come on the 27th so should I wait it out cuz it might come