I don’t understand these changes

Vanessa

I never miss my period (even when I’m super stressed). This month I missed my period by 4 days and pregnancy tests and blood work came back negative. I got my period for only 1 day on the 5th day after missing it. This is not normal for me. I’m feeling frustrated not so much because I’m not pregnant but more that I don’t understand the change in my cycle. Any advice?