I honestly have no clue

So I have extremely irregular periods due to birth control so I haven’t had one in like 4 months. I had sex a few days ago without a condom and during that little break between birth control packs/months. I have no idea like if I could be pregnant or not but I just got this weird feeling that I was and that there was something inside of me. I can’t take a plan B because I’m overweight and I don’t get periods so I have no indication of whether or not I’m “late”. does anyone have any advice or anything? I just really do not want to be pregnant lol