Date Confusion


Im quite confused.

My LMP is Sep 28, did IUI on Oct 11, Tested BFP on Oct 25.

I had a u/s today and thankfully everything looked okay - saw a sac, yolk sac, etc… but it showed 5 weeks 5 days. When I calculated, was told I should be 6 weeks 5 days or 4 weeks? Am I really off by a week? Am I calculating it right?

The only place that made sense was that it said to take IUI week as your 2nd week then it fit. Dr. was okay with it as well and said everything looked normal.

Still just confused.

I go for another u/s on Saturday.