I'm pregnant, confused about due date!!

I'm anxiously waiting my first doctors appointment.

I had a normal period on December 21, 2014. My cycles usually last between 30 and 40 days.

In January I bled twice, in the 22nd I had a very dark brown very thick mucus like discharge that I thought was my period. It lasted on and off about 30 hours.

But then on January 30th I bled very bright red for about three hours then it stopped, but cane back for about one more hour later that night. All in all I'd say I bled enough for one tampon.

I finally took a pregnancy test a week ago on March 5th. Actually I took five and they were all VERY DARK POSITIVE.

So I guess I just need some experienced women's opinions. When do you women think I conceived??

The suspense and anxiety is driving me crazy!