Ok, now I'm 16 weeks right about now. Mean and my ex had intercourse on jan 31 coming in to feb. Now I started my period around the 10th and that was my last one. Now We broke up and I started to talk to this guy and had intercourse on feb 28. Now I'm four months pregnant and Im confused need help.

You had intercourse 18 weeks ago (January 31) with #1 and intercourse with #2 (February 28) 14 weeks ago. My guess would be #1 BUT the only way to be positive is to wait until the baby is born and then have DNA testing.