When will your sixth week begin? It sounds like in about five days, if you think you ovulated on the 6th of April.
If your periods come every 28 days like clockwork, and have for years and never vary by as much as a day, and if your app said ovulation was on the 6th based on your last period beginning on the 23rd of March, the first guy could be just a bit too early to produce the pregnancy.
But if the lengths of your menstrual months vary, using the crown-to-rump measurement of the embryo to try to determine the conception date is a better way to go. If your periods aren't like clockwork, you don't want the doc or the ultrasound tech to use the first day of your last period as the start point for your pregnancy. Either ask them directly not to, (you can tell them that your cycles are too irregular to begin the count with that day) or you could even just say you don't remember when your last period began.
Hi Kate! You seem to be knowledgeable and to have done your research. I would lean heavily on ManB because of the greater exposure and better contact close to ovulation. ManA was more than the usual 5 days before ovulation. If ManA used no contraception and ManB always did I might be less certain.