6 week scan help?

CJ

I had my 2nd ultra sound today. 6 days ago, I had a 5 week scan and my gestational sac was measured at 5 weeks 5 days. Now today, I came into my ultrasound expecting to be around 6 weeks 4 days. They measured my fetal pole at 6 weeks. I don’t know what the CRL was. She didn’t tell me. The heart rate was 105. I’m a little nervous I’m measuring behind. How significant is the gestational sac in regard to being measured for how far along you are?