Pregnancy according to LMP

Hayden
I know pregnancy is measured by your LMP, but what if you ovulate way later than that???? Like for example:
My LMP was November 30th, pretty sure I didn't ovulate until December 28/29th.  So how in the world could a doctor say that it's accurate?
I'm still waiting to take a HPT because I still have 6 more days to wait.....it would be over 4 weeks off if the doctor didn't specify LMP or ovulation date... That could be dangerous.
Does what I'm thinking make sense?