I had the same delayed period last month, i did series of blood test & urine test. All was negetive. I went to see my doctor, he told me its just a change in my period lenght. But i'm not very sure about this because i havent met anyone with such story.

I worked in womens health for a number of years. It is not unusual for a womens cycle to change over time, for a variety of benign reasons. If other symptoms/changes occur such as intensity of flow, cramps, pms symptoms etc. then a revisit to the doctor always a good idea. Hope it resolves for you.