URGENT//CURRENT MOTHERS

I had a period that began on february 7th and ended in february 13th. from the 15th-17th, him and i had sexual intercourse multiple times. but on the 18th him and i broke up and on the 19th I made the mistake of sleeping with my ex, unprotected. From the 15th-21st, i was ovulating and on the 20th my boyfriend and I got back together so we had sex together... my new period was supposed to start on the 5th, but i am four days late. I took two pregnancy tests and they both came back positive. How do I know who the father of my child is...? Is there a way that the father could be my boyfriend or is there no way to tell since the dates are close?