why is my period late?

Okay so eve says I'm 4 days late however I don't normally start until the 36ish day of my cycle (which was yesterday) I have had my normal pms symptoms like sore boobs, acne, headache, cramps.. everything I normally get. I did go to Cornwall with my boyfriend and every time we had sex it was protected with pull out. We also did it protected about a week ago. Could this have delayed it?