Ultrasound...

Leah • ✨Leah✨PCOS 👣🌈 Angel baby 12-13-17 👶 Arianna Kaitlin 8-24-09💜 Engaged 💍 Rainbow baby due 11-21-2020 🌈

So today I should be 8 weeks exactly but went for an ultrasound and my baby is only measuring 7 weeks 2 days... is this normal? I also had an ultrasound last week on the 6th, I was 7 weeks 1 days but baby was only measuring 6 weeks 5 days. Should I be worried???