may +/- 2weeks po kase ang basis ng age of gestation. mostly sa ultrasound, sinusunod yung laki ng bahay bata o laki ng baby sa loob and dun nila sasabihin how far along is your pregnancy. pwede kasing maaga naconceived si baby. normal naman po yun as long as aware ka sa date ng LMP mo, wala po problema yun.