Dating scans become less effective and correct the later in pregnancy they're done. So dating now when the variation of what's normal is far wider is not going to be very accurate - not that dating scans are ever particularly accurate True IUGR (intrauterine growth retardation) can only be judged really by the same operator, doing the same measurements over a significant period of time. It sounds to me though like your babe is growing perfectly to their own timetable. We never know how long gestation will last because each baby grows to their own timetable, we only know that anywhere between 38 and 42 weeks is a normally cooked baby. And since each of us varies in size, and babies even more so, there is no real way to judge how large or how pregnant someone ought to be, yk? Sounds like you're on track to me