Period 18 days late/ 5 negative tests. What the heck?

Hi everyone, my husband and I are trying for a baby but had something unusual happen this cycle. I usually have longer cycles (35 days average) my last couple of cycles were about 41 days long.

I originally thought I was pregnant and have taken multiple tests that were all negative.

I usually spot right before my period, and had a little bit of spotting and cramping last week but it has since stopped.

Work has been stressful but I have absolutely been more stressed before without any changes to my cycle.

Hoping to see if any of you have had this happen and what the outcome was? I am planning on talking to my OB to see what’s going on.