Help!

[mrshill]

Hello, I REALLY need help! I had sex April 6th (no condom but pulled out.) April 10th I started my period. I had sex again early morning April 12th (I was still on my period). My period basically was over the evening of the 12th cause I wasn't bleeding later that day or anything so my period was two days usually it's 3 or 4 days. I've heard sperm can live in you for a few days so is it possible that I could of been fertile on my period? I had sex a few times later in April from the 19th & on basically later in the month. I took a pregnancy test which was very faint on May 7th which was positive I took another test at the Dr's office which was faint also but positive. I had an ultrasound about 2 weeks later and I was told I'm very early in my pregnancy and my due date is January 15 2015. I know the Dr's go off your last menstrual and ovulation but is there a chance I didn't ovulate when the Dr's think I did? I counted backwards like people say to do and I end up with the last day of my period but the dr said I didn't get pregnant when I had sex on the 12th of April cause I wasn't ovulating & the ultrasound is showing I'm very early. So I'm confused and it's very depressing. Could I have gotten pregnant on the 6th or 12th of April or was it later in the month that I got pregnant? I know I made the choice to have sex and I have to deal with it but I really would appreciate a little insight please! Thinking about this is driving me crazy & I'm trying to be happy but I can't help but to be depressed. Thank you.