Due date???

Sarah

I just had my first scan done and now i have no idea of my due date????? my LMP was on the 11th Aug, which means about around 6 weeks 6 days, but during my ultrasound the crown to rump length was 1.7mm which indicates 5w4d and the gestational sac measured 22.6mm which indicate 7w2d. Some help please?? oh also my HcG was 2254 last Monday.