story time....but I need help!

Okay so about 3 weeks ago I had sex without a condom and I'm not in birth control or anything. Anyways we had sex like 3 times that day and tbh I don't really remember much of that night because I was really high (don't judge) anyways I took a pregnancy test a couple days ago and it came out negative but I last Friday would be week 2 that I've been late. I've been sick for the past week and a half. I just want to know if I could be pregnant or not I'm wanting to find out. And also after me and this guy have been together for a month, the last time we had sex he left me to go back to his ex girlfriend and I havnt decided whether I would want to tell him or not. Idk I need advice and help!!