I have had two fant positive pregnancy test in the last 3 days. My period was supposed to start…

I have had two fant positive pregnancy test in the last 3 days. My period was supposed to start today and if has not. I am normally always on time never late. But the nurse at the Dr office told me I can get a false positive if I am not 7 days late for my period. I need to know if she told me the right stuff of not. This would be my second baby. My son is 8 months old. I remember being only one day late the last time and I got a positive right away.