Ghosted...Chance of pregnancy? UPDATE

I had recently moved back to my hometown and someone that I knew from a few years ago contacted me. After a few days of talking we decided to hang out. He was being really sweet and I was having a really good time. We ended up kissing and later that night had sex. I asked if he had a condom and he got one but during he stopped and said “oh no, I just did something really stupid”. I started freaking out and asked him what happened and after he fumbled around for a few seconds he said “nothing” and continued. Afterwards, he got up to clean up and I noticed that the condom was on the bed with NOTHING in it. He completely ghosted me but I’m freaking out and wondering if I could be pregnant. Honestly, I wasn’t worried until three days later when I started cramping and have lower back aches. Yesterday I started feeling nauseated. Then I checked my ovulation days and one fell on the day that we had sex. Could I be pregnant? If we had sex on the 6th when is the soonest that I can take a test? I already know I’m a serious idiot 🤦‍♀️

UPDATE: I’m four days late but the first response test I took looked negative. I should have a positive pregnancy test by now if I am pregnant, right?