saiz kandungan x sama ngan size baby

Hye..ada x yg alami mslh mcm sy...tarikh period last sy da confirm ...tp sy baby 2 mgu ke belakang dr tarikh week sy skrunk..cth sy 18 weeks now tp perkembangan baby is 16 weeks...tp sy da ckp pd doc yg tarikh last period sy mmg confirm..agkyer kenapa yer...ada x yg alami mslh mcm sy