Pregnant but unsure of who the father is.... please help! :-/

My LMP was 10JAN12, I had intercourse on 16JAN12 with the person i was dating. Shortly after we broke up and I had intercourse on 04FEB12 with a friend, so not planned, and again on 15FEB12. I had a negative pregnancy test on 13FEB12, and then positive pregnancy test on 23FEB12. It was confirmed the next day with a blood test that i was in fact pregnant. I had my first Ultrasound on 27MAR12 which put me at 8 weeks and 3 days. According to that calculation My EDD is 03NOV12, which makes me currently 20 weeks and 3 days today (19JUN12). On 16JUN12 I had my 20th week ultrasound and the tech/doc person said I was around 21 weeks. I guess my question is who could be the father??? I need to know because the man i slept with on the 4th deploys to Afghanistan in a week and I would like to be able to tell him for sure. All the math I have done points to him...