Pregnant by which man ?

I’m pregnant, but was active with 2 men. My current man and my EX.
My last period was 5-29-09
I was with my EX the whole month of June
I was with my current on July 17th and after
I tested positive on Aug 7th so that makes me about 11 weeks according to the calculator.

I feel this is my EX’s baby and I got pregnant some time in June because July 1st I’ve already missed my period and by July 17th I’m atleast 2 weeks passed a missed period, I was already pregnant when I got with my current and didn’t know it. This is my thinking. This is not a case where I was with 2 men within 10 days. I ovulated in June and was with one man in June.

What do ya’ll think? Is there a chance I could be wrong. I also don’t see where I can have sex on July 17 and have a positive test on Aug 7, that’s 3 weeks from possible conception.