I just checked the UK Fertility Friends calculator using your dates and I am getting you are 5 weeks 3 days and due 21st May 2010. I had a mess up with dates as well from scans and my second sonographer got very angry with the first one for confusing a very simple situation. It annoyed me because I got excited about thinking I was a little more far along than they had first said (although by only a couple of days) but as the second sonographer said it would be impossible to count conception from a couple of days earlier than when they actually put egg and sperm together!!!