According to my LMP I'm 7w3d. I tracked ovulation and ovulated on CD21 so I've made my due date based off that. According to ovulation I am 6w6d. (YESTERDAY 6w5) I went for an ultrasound and measured 6w3d crown to rump and she measured baby twice   It was in between 6w3d-6w4d but saw 6w3d was the one she kept. Heartbeat was 132bpm. Should I be worried I'm off by 2-3days.