Confused

G

Okay so i took a pregnancy test last week and it came back positive but had a faint line. A couple days later i took another test to see if the line had gotten darker, it did. I called the doctors to schedule an appointment to confirm a pregnancy. The appointment was scheduled the next day. I get to my appointment and they wanted to take some tests because i had very uncomfortable cramping. They drew blood, they did a transvaginal ultrasound and everything looked good! Later that day the doctor gives me a call and she said that the test is negative, I’m not pregnant. Today makes me exactly a week and two days late on my period. Can anyone explain to me what this means? Pregnancy test showed up positive but blood test was negative and blood test are a lot more accurate, so i came to the conclusion I’m not pregnant. however i still haven’t gotten my period.. I’m so confused.