5 Days late, negative HPT

My periods are very regular and I’ve never been more than 3 days late, I have never skipped a period except when I was pregnant with my daughter almost 5 years ago. I’ve taken 2 HPT and they have both come out negative. Has this happened to anyone else? What was the outcome? I feel stressed out just from not knowing what’s going on with my body. 😩😩😩