Not sure who the father is??

I AM ASKING FOR A GUESS. 
PLEASE DO NOT TELL ME TO GET A DNA TEST AS IF I DON'T ALREADY KNOW THAT... 
Hey ladies. So yesterday I went and got my first ultra sound. They told me that the baby measured out at 7 weeks. I asked the lady working there if she could tell me around the time I ovulated and she said around mid December. She said between the 15-19th. Well on the 11th and 12th, I had sex with this guy. He came inside of me. And on the 19th I had sex with another guy but I'm pretty sure he didn't even cum at all. I forget what all happened but I know he didn't. He kept stopping. But then on the 24th of December, Christmas <a href="https://play.google.com/store/apps/details?id=com.glow.android.eve">Eve</a>, we had sex again and he came but he pulled out. My periods are really irregular. The first date of my last period was November 27th and it lasted 7 days. Usually I only had it for 4 or 5 days but that time was alittle bit longer. So, based on the info, can anyone help me out on who they THINK it could be?