I had a period on june 21. had unprotected sex june 30 & july 6. on august 10 i got a ultrasound saying my due date was april 5. when did i conceive?

Probably July 6: The ultrasound is fairly accurate at that time in pregnancy. According to the due date, you would have gotten pregnant around the july 12. The closest unprotected sex would be the 6th, but the ultrasound at about 6 weeks is usually more accurate than that, suggesting that you got pregnant later than the 6th, but the 6th is still possible.

July6 to july 11: Your date of conception is anywhere between july6 to july 11.That means you got pregnant when you had sex on july 6th.