My period's are very irregular. My period in August 2011 was on the 2nd, in September 2011 was on the 5th and October 2011 was the 10th. My period in October 2011 only lasted 4 days, and 2 days after my period ended I had a lot of clear, watery fluid. I had sex with a friend on the 16th and I had sex with my boyfriend the 17th up until now. From the 24th-28th I was feeling really horney, my boobs were so sore, and I had the sticky egg white fluid, not a lot though. I am now 5 weeks pregnant I went for a ultrasound when I was only 4 weeks 5 days and they said they could not see anything as I was not far a long enough. Do you think I got pregnant around the 16th or the 24th of October 2011?

Your dates are too close to know either way. Only a DNA test will let you know for sure who the father is.

You could have become pregnant from either the sex on the 16th or sex afterwards. Your body may have been preparing for ovulation (the egg white like discharge is often an indicator). If your body is close to ovulation, sperm can survive for several days... otherwise they die off quickly. Most survive about 2 or 3 days, but some even a few days longer. If you happen to ovulate on the early side of the norm, as some women do, or even just happened to that cycle, your friend could be the father..

Odds are greater that the baby is your boyfriend's, simply due to average timing, but again, DNA testing is the only way you will know for sure.