hi, the first day of my last period was July 1st and i slept with my ex on July 5th. We were broken up and I slept with the guy I've been seeing for the first time on July 16th and the morning of the 17th is there a chance it could be my ex's ? My due date is April 11th from my Dr but the sonogram lady said the 9th and the specialist said the 8th