Ultrasound question!

Hey ladies !! Had my first ultrasound today. By my last period I thought I was 7w6d but the tech said I was measuring 8w5d. Does that mean I’m actually 8w5d? Or just baby growing healthy and I’m still 7w6d? She did change my due date from June 27 to June 21, so I guess it’s a dumb question. But how does that work?☺️