Morning After Pill: What to Expect & What Happens Next

Question
Hi, around the end of July I had been having issues with my bf and we took a little break, I had gone out one night with some friends and got very intoxicated and slept with another man without protection. This happend early in the morning around 4am. That following Sunday I went out and got the morning after pill and took it around 3 in the afternoon. A couple days before this incident I did sleep with my boyfriend and again a couple days after. About a week and half ago I found out I was pregnant. I went for my first ultrasound the other day and they told me I was 7 weeks and 2 days along. Which puts me around the time of sleeping with this other man. Now I am worried and upset that I do not know who might be the father of my baby. Any advice?

Answer
Assuming you took the morning after pill the day after you slept with the other man, it's much more likely that you are pregnant by your boyfriend.  However, the only way to be certain about that is through paternity testing.  No ultrasound can pinpoint the exact day of conception.  Paternity testing can be done during the pregnancy by means of amniocentesis or CVS, where placental cells are removed through the cervix, or more easily after the baby is born.