I`ve just worked out on my calender that it`ll of been the end of april prob around the last weekend.(this depending on if your 28 day cycle) to work it out just count 40 weeks back from the 17th jan which takes you to 12th april, which should be around the time of you period that month then go ahead 14 days if you cycles 28 days, go 16 days if your 30 day cycle and go 18 days if your cycles 32 days, this will of been wen you was most likely to have conceived, hope I`ve been of some help