Due Date Mistake

Everytime someone asks me when I am due I usually told them March 10. But today when I went for my checkup I found out that my original due date is March 15. Then when I got the second ultrasound I found out that it got changed to March 8. But the nurse told me that the original due date is what they go by. Now I am all confused on the dates. All I know is the baby will come out when she is ready. Or unless there is a need for medical intervention...or hopefully not. So FYI everyone, my baby will be here during the month of March...:)