HELPP! NEGATIVE BLOOD TEST

I am currently not using any form of birth control and me and my SO have been a little irresponsible this month. I am now a week late on my period which is completely abnormal for me. I took 3 test at the beginning of the week one had a vvvvvfl and the others appeared negative. My doctor also did a blood test early in the week and it was negative as well. I’m so confused as to why I still haven’t got my period and I’m not having any symptoms of it coming soon. Is it possible I took the blood test too early and it’s a false negative? Should I try to retake a hpt?