My LMP was December 30th and it lasted 3 days. Generally my cycles are 26 days, but sometimes 24-25. I had sex January 8th with no protection and there was ejaculation. I then again had sex on the 14th of January (I don't believe there was ejaculation), and took Option 2 , 5-7 hours after. I took a test on on January 22nd that was negative, but then a positive on January 26th that has been confirmed. When did I conceive?  I have an ultrasound at 7 weeks, will I know my date of conception?