Okay I need some input. Went to have my first US today and thought I was 7 weeks 4 days. The US tech measured me at 5 weeks 5 days, so two weeks off. The HR was 115 and very strong. Have any of you experienced your weeks being off this much? I mean, I took ovulation tests and everything and really thought I had this down to a science. Any input or similar situations are greatly appreciated!!!