29/1/2013 11w1d crl 44mm.. 4/2/2013 12w1d crl 56.3mm .. edd 18th .. irregular cycles.. did i get pregnant november? is 6th dec possible date or not?

A gross estimate: An ultrasound estimate of gestation at 11 weeks is not as reliable as in earlier gestation, say, 6 weeks. I counted backwards for you that 11w1d from 29/1/2013 would be nov 12, the onset of your last menstruation. If ovulaton took place 14 days later that would be nov 26. I will be the first to admit that this calculation is far from precision.