Who Could Be The Father?

Please don’t judge me, no one is perfect. The guy I was dating(Guy A) started being really distant and didn’t see me for almost a month and a half before this. I hung out with a friend(Guy B) and got really drunk on May 19th, ended up sleeping with him and did the pullout method. When I got home I had alot of ewcm. The guy I was dating(Guy A) came back around on May 24th and we slept together. During sex he so called joked like he was coming in me, but denied it after. My period was supposed to start May 31st, but I got implantation bleeding for 3 days instead. I took tests all the way up until June 4th to get a vffff positive because I was getting symptoms and the spotting. I conceived with my 1st son around similar dates, sex was on the 22nd and period never came with a positive on 4th of the following month with him. Could Guy A or B be the father? I know sperm can live for up to 5 days. Could a dating ultrasound tell the exact date of conception?

Update: As of 06/06 my hcg level was 21