Thanks ladies. Thats what I thought. As it was unplanned I've never known when I ovulate (measured temp etc) so will have to get paternity test once baby is born and try not to stress about what I'm goin to say to the men. My mum thinks I should wait til I have my 1st scan and am past the first trimetser before telling them.
You can not really pinpoint conception - you could ovulate late/early or the sperm can live for 5 days - The only way to tell is a paternity test with intercourse with more than one man in the time frame give above. good luck.
I would say since the dates are so close together you are going to have to have a paternity test when the baby is born to definitively tell who the father is. Usually early ultrasounds are extremely accurate. Be honest with both of the guys and then the only thing you can do is wait it out.