Any ideas???

I would like some help trying to figure this out... I am 6 days late on my menstrual cycle and my spouse and I do our best to avoid sexual contact during my fertile stage because we want to wait a year before starting a family. And I am trying to figure out what it is. We PCS'd (military move) to a new base that is outside of the country about a month ago and I already had 1 complete cycle since being here so that is making me doubt it is due to stress like in previous times .... Help....