Who’s the dad (help)

No judgement please, it’s driving me crazy not knowing. I have no history with guyA he was just a partner for a week or so my last period was dec 11 I had sex with him dec 15&17 I have irregular periods always have so it’s harder for me to tell. GuyB I had sex with dec 29, 31st,1st,2nd,3rd I have two apps on Flo it said I was ovulating with guy B but glow said I was ovulating right before guy B my LMP says I’m 12 weeks and convinced dec 25 but sperm can’t live that long can it? My first ultrasound sound I was a week behind so I assumed it was guyB then I had another one this week and I’m on track just a couple days behind. I took a test around dec 29- Jan 3rd and it was negative but I took another test Jan 12 and it was positive to me it seems like guyB but I want to know what you guys think

BTW GUYA DIDNT NUT IN ME but I heard there is still a chance when they go back in guyB did nut in me multiple times