I am currently 20 12 weeks pregnant, my due date is august 16, I had sex on the 2nd of November, we used protection, but we were also drunk. I can't remember if I had a period after that, but I think I had it around the 9th. On the 14 of November I started dating a boy whome I have known for a very long time, we had sex on the 24 of November, we did not use protection, but the next morning I took plan b, but at the time I was 172 lbs and I read that plan b is iineffective if you weigh over 170 lbs. I went to a doctors appointment where she gave me a due date( August 16) my question is, how accurate is the due date, and is there any chance the first boy could be the father. My boyfriends family is so involved and we are planning on getting married, I just need to know if it is his for sure, I know it sounds terrible, but I just need to be reassured.