please Respond

I am currently four days late for my period. I have taken a test a day all negative. I am never ever late. I am always stressed so that has never affected my cycle. I have been dryer than usual this month. I am worried that I may have lower estrogen levels for some reason this month. Has anyone been through this or something similiar. I am completly fine if I am not pregnant this month. I just do not want this to prevent me from ovulating next month. We only had sex one time this month and that was on the 8th the first day of my fertile window.