If my dating scan has assumed my LMP started a day after my period actually started that month, does that mean I roughly ovulated for a 28 day cycle? I have really messed up cycles and they can range from 35-45 day cycles. Since having my daughter they sort of regulated then I missed 3 then they were late and then I fell pregnant. But I do remember having a period 6th December, scan suggests period started 7th Dec. 3 scan dates suggest I fell pregnant that cycle