22 days late

Im 22 days late now i have taken multiple pregnancy test and even a blood test ( which I think wasnt drawn right because they only took barely 1/4 tube of blood... it was a student learning) anyway is there anything else that cna cause this im on bc and I haven't changed anything... expect my caffeine intake because my migraines have become severe again like when I was pregnant with my son ( he is 7 months old)