Thanks for the query.
Some amount of fluctuation in the menstrual cycles is common.
That can occur due to many causes like, lifestyle modifications, hormonal
and strain etc.
So you wait for one more week, possibly by that time you will get periods.
If not, consult gynecologist once and go for ultrasound
If she recommends go for hormonal profile including thyroid
By these possibly the cause for your problem can be identified and treated.
For more details you can ask me directly through the premium forum.