What the heck ??!!!

Two days ago i got a positive pregnancy test , my boyfriend was completely shocked so he bought another test , also positive but faint , so the next morning i took another and got another positive this time even darker .. today i go to the doctor to get everything checked and they said my test cane back negative? How is that even possible? The nurse said i might still be very early in the pregnancy so she gave me prenatal vitamins and told me to come back in two weeks if still no period .. im well over a month late ? She suggested blood test but at the time i was so heart broken i just wanted to go home and crawl into bed . Started reading other moms stories very similar to mine . Idk what to think !!! Whats your opinion? Have you heard of anything like this ?