I'm due the 17th as well and those were the dates I figured up for conception congrats I found out at three weeks tho since I already had two kids I know my body so it wad still very fresh in my mind
If you had your last period may 13th you most likely conceived between May 28th and June 3rd. No way to tell the exact date though as anytime you have sex sperm can live inside you for up to 5 days before meeting with the egg.