Ay, mahirap talaga mag-calculate kung hindi sure ang last period date, pero ang ultrasound findings mo ay mas accurate kaya ang February dating ay mas reliable, best to confirm with your OB kung ano talaga ang exact due date based sa ultrasound measurements, lalo na may nega pa nung May. You're doing great na nag-follow up, and soon you'll have clarity on when baby's coming, rest easy, ang healthcare team mo ay makakasama mo sa journey na ito!