Measuring ahead

Hey ladies I've been in a huge nesting and kind of stressed out mode I went to my doctors wednesday and I was 34 weeks however the doctor is concerned that I'm measuring 36.2 weeks instead of 34. She sent for ultrasound and baby is measuring 6 pounds. My first child came at 37.4 weeks on her own with my water breaking. I had no Braxton hicks or anything that warned me of her coming. This pregnancy my Braxton hicks have been a bit of a concern and muscus plug is gone already. I'm asking if anyone has had this happen before and if so was it they got the date wrong, did you go early, did the baby really weigh a lot? I'm just worried that since I went early with my first I'll go early with my second again. Thanks!