Confused due date

LMP : June 21, 2018

- got a positive test August 18, 2018

.... August 22 i got an ultrasound measured 7 weeks & 3 days

... due date would be March 28 , today I would measure 35 weeks & 5 days

..... I had my second ultrasound TODAY. ( different clinic ) they told me I measured 33 weeks & 1 days

.... my LMP was June 21, 2018 which makes sense with my first due date March 28

But now I measure different & have a different due date . I’m so confused which one do I base off of !?