LMP or Ovulation??

Keisha

Hey everyone I’m new here! My LMP was 12/22/2019 but through tracking of OPK’s I ovulated 1/13/20. So LMP puts me at a Sept due date and Ovulation gives Oct. a lot of ladies on FB said doctors go off LMP. How is everyone calculating theirs? Was yours off much when you wen yo your first scan?