Pregnant???

My fiancé and I have had unprotected sex several times within the month. Five times to be exact.. If that matters. One of those times, I was in my fertile window, but only the first day of being fertile. I'm now 3 days late on my period and I've been keeping a tampon in, just in case. While changing the tampon today, I noticed a very thick white mucus with sort of a light yellow tint to it... I was doing research of yahoo answers and most of the answers said that it's a sign of pregnancy. I was curious if this has ever happened to anyone else before. Do you think that I'm pregnant?