PLEASE HELP ME OUT!!! I’m not 100% on who my baby daddy is😖

July 3rd- had one night stand with other guy. Never slept w him again. Got my regular 5 day period 3 days after the hookup.

July 22nd- I went to my gynecologist because I was having weird smelly discharge after the hookup, first thing they did was a pregnancy test it was NEGATIVE. They also tested me for stds and it came back positive for chlamydia. And I got treated

July 29th- me and my current boyfriend started dating, and had sex regularly. I started another regular 5 day period in the beginning of our relationship.

August 21st- I went to my gynecologist again bc I just felt like I might still have chlamydia, something just felt off in my body. First thing he done was run a pregnancy test and it was POSITIVE.

August 21st I also went to the Er late that night with pretty bad stomach cramps. I was convinced it was an ectopic pregnancy so the done an ultrasound. They couldn’t find a SAC or BABY. They told me I had just missed my period and it was just too early to tell anything. My hgc levels were only at 300.

I am now 18 weeks pregnant with a healthy baby boy. My due date is April 28th, people recently started saying and spreading rumors that the baby is the guys from the one night stand I had July 3rd instead of my boyfriends baby. I’m promising my boyfriend there’s absolutely no way, but in my head I AM SO SCARED!! Anybody that knows anything ab the reproductive system, PLEASE PLEASE PLEASE help me out!!!! Is there ANY WAY POSSIBLE THIS BABY IS FROM THE ONE NIGHT STAND FROM JULY 3rd???