Feeling hopeless :( so long but I need your ladies words :(

I've been with my bad for years. Last October we split up. I ended up getting my period the 11th of Nov but then ended up sleeping with someone else the week I should of ovulated. Then me and my bf ended getting back together the first week of December. I ended up bleeding on Dec 11th and also had to go to the hospital for what seemed like food poisoning, they did a hcg blood test that said negative. I ended up getting pregnant the end of December. The 31st I took another test because I was scared I was still preg from the other guy, negative. That would be a month and a half from my period in November. I ended up getting a ultrasound at 8 weeks matching right to my bf; and my 20 weeks one was pretty much right on. I know I shouldn't freak out because of the tests and period. But is there anyways I'm 2+ weeks ahead and it's the other guys and I don't know? I feel horrible and I'm constantly stressed. Thanks for advice