What affect irregular cycle?

Alright so I read so many things about it because I'm 6 days late now and I already took a pregnancy test (the result was negative and I always had protected sex), I've been stressing and anxious a lot because I was late. And I was trying to figure out what else that makes me late. So yeah, this month I went through so many things, I was drinking a lot and smoke a few times (like only 3 times). I read in some site that drinking and smoking could affect the cycle, but in the other site, it doesn't affect at all. So I was kinda confused, does it have much affect or not?