Nervous and Confused

So, my period was due on the 17th. I felt cramping and my normal hormonal headache the day before. Nothing abnormal. Then my period didn’t start. 18th, 19th, 20th all passed by and today on the 21st, I had a tiny amount of pink blood and some mucus. I have tested every day since the 19th with undiluted morning urine and have had the most clear negative results ever on 3 brands. I only spotted for a couple of hours today, and otherwise… nothing. I’m a little nauseous/acid reflux, still crampy (all week), and headachey and tired. Nothing but negative tests. I’ve gone through 2 pregnancies and this is nothing like those experiences, but still… anyone have a similar experience? What was your result? Weird delayed period or weird delayed positive test?

Since my first period 17 years ago, I’ve never been more than a day late. Not even when I was super stressed (which I’m not now)…

Help! Advice?