It sounds most likely, from the first ultrasound you had, like you conceived around January 11. The second suggests January 9. Neither of them strongly suggests the second guy, they are both before he came along. Don't use anything from the ultrasound at 20 weeks to try to determine a conception date. They are less and less accurate for dating purposes as a pregnancy progresses.
Thanks for the input. Do you think it'd still be a good idea to get the DNA test done just in case? Guy1 isn't in the picture at all, and Guy2 said he's willing to do the test if it's necessary. When I found out the gender of my baby at 16 weeks (a girl), they also gave me a due date of 10/7. That's why it's a littler nerve racking...
As I said, ultrasounds are less accurate for dating purposes as a pregnancy progresses. The early ones are the ones for dating a pregnancy. When the baby is born, get a DNA test, so you will never have to wonder (and will never have false hope either). I'm sorry if guy #1 is a jerk and guy #2 is nice, because everything of significance for dating the pregnancy points to guy #1.
I have a feeling it's the first guy's child. But regardless, I still plan to do this all on my own if by some miracle it's the second guy's.
I'm just happy that my daughter is healthy and she'll be born into a loving family (which include three siblings) regardless. Thanks again for your help!