Hello I really need advice,I’m currently 18 weeks and 2 days pregnant. On the 5th December 2017 I had a scan and I was exactly 13 weeks. I saw my midwife this week and she told me I would have conceived the first week of September 2017. I’m confused as every conceiving app iv done shows I conceived later than the first week of September, my due date is the 12th June 2018 I really need a second opinion as I don’t know who the dad is. When did I conceive?