What does "I didn't know my Imp" mean?
Generally, those types of determinations are made by measurements with the ultra sound and "normal" baby sizes as specific ages in the womb.I am sure there is room for variance. In this case it would mean that the baby is physically 2 weeks behind in growth rate which may or may not be the case.
At any rate, you probably want to ask this question somewhere else other than a tech support forum ... (Un)Planned Parenthood will be glad to see you and help even if you don't plan on murdering your baby.