Is measuring a week ahead in the 2nd and 3rd trimester normal? what causes that? neither me or my fiance are very tall.

Normal: This amount of difference in pregnancy measurements is entirely normal. In fact, it doesn't even indicate well the size your baby will be. Even ultrasound scan measurements can easily be off by two weeks on the measurements in later pregnancy. It sounds as if you are perfectly normal. Shorter women often measure a little bigger since they have less room to hide the baby in and thus appear bigger.