False negatives??

Amy

My period was due on Monday, it's now Saturday and still no show at all, but random symptoms that lean toward being pregnant. My period hasn't been late previously that I can remember. All three morning urine tests over the last 1.5 weeks have been negative. Feeling confused and disheartened.

At what stage is a period considered missed? Are false negatives common? Its now CD 36.

Thanks in advance! 🌷