When do you guys think I got pregnant??

I know that nobody knows for sure but I just want some answers. My doctor estimated it and said that I ovulated around the 15-19. The picture below is what glow says. Cuz I don't know who the father is. Please no rude comments or judge. So, on the 19 I was ovulating I guess according to glow and what my doctor said but the guy on the 19th didn't even cum at all. I know there pre cum but he didn't cum at all.. It's a long story why. His little sister kept barging in the room. But if it is him, I did get my positive pregnancy test on December 26. I don't know how it would of came up that quick. Usually you have to wait 2 weeks??? Idk. What do you guys think??