Confused about u/s

Went to the ER last night, thank god baby is ok, had an u/s and I'm suppose to be 8wks 4days yesterday but the report is saying the baby is 6wks 2day. Ok if that was true then that means on March 8th when the ER got a strong positive urine pregnancy test I would have only been 2wks 3day. I dont think that is possible. I'm confused.