Ay, ganyan talaga ang nangyari sa akin din nung pregnant ako with my second! Kaya nag-rely ako sa ultrasound dating kasi mas accurate yan, lalo na if di ka 100% sure ng LMP mo, ang doctor ko that time said the first trimester ultrasound is more reliable than guesswork. I'd suggest go back to your OB and let them confirm kung aling date ang gagamitin nila officially para sa records mo, kasi minsan may slight difference lang talaga between LMP calculation and ultrasound, pero they'll pick the most accurate one for your due date at monitoring. Good thing nag-ultrasound ka na, so at least may concrete imaging na basis!