I got my period either Dec 27 or 28 and the last day was on January 1st. I had sex wit my current boyfriend on Dec 26, January 5,11 and 14. I unfortunately had sex wit an ex on January 1. I was wit my ex almost 2 years always had unprotected sex and never got pregnant! I am due sep 29th I have used multiple calculators to estimate the conception date but none are based on my lmp only my due date. What are the chances my ex can b the father?