I've been having a few symptoms, and I sincerely thought I was pregnant, so I took a test at night, the day before my period starts. It was a negative, but it was a dollar tree test, and it wasn't first morning urine. I still haven't started my period and I am insanely regular. I start every 28 days in the morning, and I am a few days late, with a negative. Could it be false? How common is that?