Period 12/10 for 3 days. sex dec 13th. spotted/bled 12/24-29. was on depo-provera but didn't get shot in july. sex jan 7th-12th. now 7wks preg. which event?

The latter: Based on a last menstrual period of 12/10, your average date of conception would be on or around 12/24. That would put the pregnancy at 9w and 5d. This doesn't sound like the date of conception as it's off by more than 5 days (it's off 2 wks, actually). If conception was on 1/7, then you would be 7w 5 days, so more likely it was the second encounter that lead to your pregnancy. Hope that helps!