Data about the length of your menstrual cycle was not given. The ovulation occurs two weeks before the end of the menstrual cycle. Assuming that your menstrual cycle is always 30 days long, you should ovulate at day 16 after the beginning of your period. The ovum is ready for conception till approximately 24 hours after ovulation. Given the fact that you have an irregular menstrual cycle length, the most probable date for your conception would be from 7 November till 14 November. The eighth week pregnancy should be checked with an ultrasound and even then the embryo might look different than the actual maturity.