I'm a week late on my period and I'm never late. I have been having regular periods for over a year and I took 3 pregnancy tests and they all showed up negative. I was talking to one of my cousins about it and she told me that she had taken a pregnancy test with her second child and it gave her a negative sign. When she went in to the clinic they drew blood and it showed that she was pregnant. Is it possible for a pregnancy test t be wrong 3 times in a row?