Doubt

I’m feeling really down about a situation I posted about a few weeks again My last period was January 6, 2020 my due date is October 12, 2020 I slipped up with someone else on January 25th 2020 and it’s really bothering I feel like I was already pregnant at that point because I found out I was pregnant on January 31st and everything adds up but I’m having a lot of self doubt and it’s killing me maybe it’s just google getting in my head . But either way I feel like crap for this happening