Uy, first time mom ka rin! Yan ay normal lang actually, a few of us had timing differences din between LMP and ultrasound age, kaya don't stress too much about it. Babies develop differently, and ultrasound measurements can vary especially if dating ng LMP mo wasn't super accurate or if conception delayed a bit, so 3 weeks difference is within the range na docs usually see. Best talaga na i-clarify lang with your OB kung ilan exactly ang age nila based on the latest ultrasound, para sure kayo on the due date. Congratulations, mama!