Paternity issue.. need help!?

Here's my situation... I had sex with my ex-boyfriend on Nov. 3rd and exactly 1 week later (Nov 10th) had sex with another person which just happened to be on my most fertile days. I got an ultrasound on January 12th saying I was 10 weeks and 4 days along. I had only had sex with the other guy 9 weeks ago, yet the doctors say he has a better chance at being the dad and i dont understand how when the ultrasound is saying i'm 10 weeks and 4 days and it would have only been 9 weeks since i had sex with him..wouldn't that mean the baby is my ex boyfriends bc of how far along i was? I know ultrasounds vary but i heard they only vary 4 days. also I had a period in november but it was very weird and light and i was told it couldve been implantation bleeding or something but i didnt have one at all in decemeber. i know the only way to know for sure is a DNA test after my son is born but i jsut want to hear everyones honest opinion on whos they think he is... my ex boyfriend or the other friend

Since you had sex with two different me so closely together it be either could be the father. Ultrasounds readings can sometimes be different from time to time. You are going to have to wait for the DNA test. When you have unprotected sex with different partners it is easy to be in the situation you are in. It happens to people all of the time.

Girl, what a mess eh!
Is there a way that they can test for the date of conception?
Can they test you while you are still pregnant to see who the father is?
How far into your cycle were you when you had sex with each guy?
Otherwise, have your baby tested after he is born to find out who the father is.
Do the guys know that you are uncertain who the father is?
Good luck!!

Ultrasounds only give an estimate of how far along they think you are based on the development of the foetus. If your foetus is large, then that could be why the ultrasound is saying 10wks 4 days.

Basically, your doctors are saying that the 2nd guy is more likely the father - I assume that this is based on when you had your period last (which you haven't mentioned) because this will indicate approx when you ovulated (i.e. when you were most fertile).

You can only be sure though by getting a DNA test when baby is born.