Hi there and welcome! Well, truthfully, even the most regular of gals will have the rare/occasional off period. Definitely, being ill, having stress, taking medication, changes in routine, etc. can cause a period/cycle to be different than our norm. I agree to stop any intervention to get a period that is four days late. Honestly, being late occasionally is very normal and nothing to be concerned about. Unless you've had unprotected sex, I would not worry nor try to make your period come when it is occasionally late. If you had unprotected sex, then you need to take a pregnancy test.
Out of nowhere several years ago, my thyroid slowed down. My cycle went from every 26 days to getting my period once every 3 to 4 months. It righted itself after a year. Even with that, my doctor was not overly concerned. Had it gone on, we would have treated my thyroid issue. So, a few days longer cycle is not in the realm of gynecology something that I'd worry about hon. good luck