This can't be happening to me ......

So 3 months ago my fiancé and I broke up. I found out he was talking to a long lost friend I had never heard of in 2 years NON STOP BEHIND MY BACK!
Well time passed and me and him still love eachother. We do occasionally hook up aswell. But I also met a guy. And we started hooking up not in a smart way. All I know is that I feel weird. If I was to be pregnant can a doctor pin point exactly when I got pregnant?
As horrible as it sounds that's the only way to know who the dad would be. 😣