I had sex on the 30 Nov 2012 and then had sex on the 5 dec and now I am pregnant. My due date on ultrasound is 31 August 2013. Will I have fallenpregnat from sex on the 30th or on the 5.

It is impossible to know when conception happened with encounters so close together.

Based on the conception calculator, you conceived somewhere between the 4th of December to the 12th. It states your LMP was around the 24th if November. Although its still possible to ovulate 6 days after your LMP, its not likely so I would say the 5th is more likely. Good luck!

And those conception calculators are based on an average monthly cycle of 28-30 days. Not all women ovulate like clockwork, so these calculators can be highly inaccurate.

My LMP was the 22 Nov 2012.

Still impossible to know.

If you're wondering who the father is, you'll need a DNA test done once the baby is born.

How long does sperm survive and is it possible to fall pregnant on the day you ovulate?

How long does sperm survive and is it possible to fall pregnant on the day you ovulate?

Claire, gestational dating is all Best Guess, so either person could be the father of your child.
Only a DNA test after the birth will verify the paternity.