No period, 3 negative tests. What does this mean?!

My period should have started around June 22. I started the placebo week of my birth control on June 25.

I took a test at home on June 29 and June 30, both negative. My doctor ordered a urine test and I went in for that yesterday (July 2) and it came back negative.

I still do not have my period.

We are not trying to conceive at the moment. Any thoughts?