HELP ME UNDERSTAND....

Celeste • Im 27...Mommy to 2 handsome little prince's...my boys are my world.!♡♡

Has anyone thought they were so far along and than get told they're actually a lot earlier than expected.?!?! I have 2 apps, one says I'm 7w1d another says 6w1d....

My Dr thinks I'm earlier than that....how can I be so far off if I know the first day to my LMP. That's what they go off of right.?!?! I'm so confused.