Early Ultrasound and EDD change

Back story... I had an ultrasound last week at 5 weeks 4 days since my LMP. Everything measured correctly qith the gestational sac and yolk sac. Went back today and saw a fetal pole qith a HB of 111 and measurements indicating 6 weeks exactly. By my LMP and my first VERY faint positive test being at 8dpo I can't see how they would change my due date. Has anyone had them change it, then change it back later? I just know there's no way I am only 6 weeks today instead of 6 +4. Pic of U/s posted as well.