EDD question !

Alysha • ❤️

Okay so when I first found out I was pregnant according to my LMP and ovulation date I was due Jan 11 and went in at 10 weeks for an ultrasound , there they told me i was measuring 2 weeks back at 8 weeks and 3 days changing my due date to Jan 22. now at my 20 week anatomy ultrasound the baby Is measuring at 13 oz instead of 10 oz. could it be possible that the original due date of Jan 11 was right or, could I just be having a big baby?