7 weeks pregnant and “negative test”

Okay so.. I found out I was pregnant when I had 4 weeks. Couple of days later I started to bleed very little so went to the doctor the next morning. Got an ultrasound done, saw a sac. They gave me progesterone to take. I’m 7 weeks now and out of curiosity I decided to take a test and it’s a negative. Could this mean it was a chemical?