Determining the exact week of pregnancy you conceived can be challenging without knowing your last menstrual period (LMP). However, we can estimate it based on the average length of a menstrual cycle. On average, ovulation occurs around two weeks after the start of your last period. Assuming a typical 28-day cycle with ovulation occurring on day 14, if you are currently 10 weeks pregnant, it is likely that conception occurred around eight weeks ago. As for your last LMP, without more information or tracking data, it is difficult to determine the exact date. It is recommended to consult with your healthcare provider who may suggest an ultrasound or other methods to estimate your due date and provide more accurate information regarding conception and LMP.