It is not uncommon for there to be discrepancies between gestational age and fetal size during early pregnancy. The most accurate way to determine gestational age is through an ultrasound measurement of the fetus. In some cases, the initial estimate may have been incorrect or there could be natural variations in growth rates. It's important to consult with your doctor for further evaluation and guidance. They may recommend additional ultrasounds or tests to monitor the baby's development and ensure everything is progressing as expected. While it can be concerning, try not to worry excessively as stress can also impact pregnancy outcomes. Your healthcare provider will provide you with the necessary information and support throughout this process.