Late period but didn’t have sex

My period is about 6 Days late. They’ve been pretty regular since I got off bc in August. But before I was on the pill my periods weren’t always exactly on time. I’ve had all the pms symptoms like sore boobs and moodiness. I have not had sex at all but I did recently start a new semester of college so my routine has changed, plus I’ve partied/drank more than before (I’m talking going out 3-4 times in the past month and staying out super late). Could these changes be messing up my cycle?