Im 12 weeks pregnant my last menstrual period was February 6, 2015
Could I have conceived on Feb 24 or 25 if Im 12 weeks now.

My boyfriend is questioning if he is the father.

Did you have sex with another guy since early February? If so, a DNA test after the baby's born will resolve who the father is. If your boyfriend is the only possibility, but he demands proof, he'll have to be tested after the baby's birth.

Yes, you could have conceived in that time frame. Pregnancy is usually dated from the start of your last period and then sometimes adjusted a bit if you have an early ultrasound.

Twelve weeks is where you would be with a period on Feb. 6 when dating from your period.

Conception dates are plus and minus a week at best and can even be off 2 weeks. They are merely estimates, as is how many weeks you are, since they are based on the dates of your last period, that you gave the doctor.

But yes the dates of 24 and 25 are very good possible dates of conception.

If you had sex with someone else during Feb, between last period and when you missed that next period, yes they could be the father also