It can be confusing when the dates don't seem to match up during pregnancy. The most accurate way to determine your conception date is through an ultrasound scan, which measures the size of the fetus and calculates an estimated gestational age. While your LMP is typically used as a starting point for calculating due dates, it's possible that you ovulated later in your cycle than usual, leading to a discrepancy between your LMP and the actual conception date. If you're unsure about your conception date or have concerns about your pregnancy, it's best to consult with your healthcare provider who can provide personalized guidance based on your specific situation.