What due date do y’all go off of?

Tiffany

I originally was selling care through a midwife and my initial appointment I measured on track with what I thought putting my date at 8/8

I then decided to go back to my Obgyn and my first scan will her was at 12 +2 but I was measuring 12+6 making my due date 8/3.

Not that it matters because baby will come when he/she is ready but I like to track growing. What would you go off of?