Hello friends... I last had my period on March 18th. In April, I didn'…

Hello friends... I last had my period on March 18th. In April, I didn't get my period. I took a pregnancy test and it was negative. May came and still no period. The test this time came positive, so I expected my pregnancy to be 11 weeks 4 days today. But when I went for an ultrasound, it turned out to be 6 weeks 6 days. I'm confused.