im pretty sure i know who the father is BUT im still doubting myself

I am currently 32 wks into my pregnancy & when i last went to the doctor she told me that my baby was measuring 1 wk ahead than she should. my 1st reaction was that both the dr & i calculated the due date/conception wrong and that I'm really 33wks and got pregnant sooner. So now I'm wondering if the guy i had sex with the week before i ovulated, who pulled out, is my babies father OR if the guy i had sex with the day before, the day of and the day after i ovulated is the babies father.

so to get a view of everything...the 1st day of my LMP was Sept. 2nd, 2010 and I usually ovulate on the 14th day so that'd be Sept. 15th, 2010. I had sex with an ex on Sept. 10th, 2010 but he withdrew before he came and then i had sex with my current bf everyday from Sept. 13th to Sept. 17th, 2010. i'm pretty sure to almost positive my baby's father is my current bf, but i wanted to find out what others think of this situation. I only want whats best for my baby and I'm scared to tell my current bf about this information that has been bugging me.

Last thing you need now is to worry and be scared even though, I know - how can you not be. But, you have to think about the baby first and everything else can be dealt with when the child is born. But, I really really doubt that the ex could have been the father - he pulled out, the sex was before you ovulated and its pure numbers - you simply had more sex with your boyfriend during ovulation. So, the doctor really did not need to scare you with all this - you know yourself that babies can be born before, even after the term and I doubt that he used some sophisticated method to determine the exact week of pregnancy. So, my advice - let this go until baby is born, chances are almost zero anyway so why create chaos.