Your period is seven days late it has not started yet your last period before that was 4 days late you have not been stressed but you have been ill just want to know why your period hasn't arrived?
We are organic beings, not machines. That is why most people have a variance in the number of days between periods and their duration.
answer stressing can cause your period to be late and being ill can as well. So you don't need to worry. Stress, age, diet, being ill etc can cause you to be late and also can cause you to have irregular periods.