One-day period??

🐕
Yo yo ok so I was gettin a lil frisky w my boyfriend, as ya do, and we noticed I was bleeding a little. It wasn't a lot, but it definitely was enough to say that I started my period. But throughout the rest of the day I hadn't bled more. This was monday. People say it might be a pregnancy but we've been playing it super safe. I'm even pretty sure every time he's pulled out with a condom (which is every time) it was quick enough. I've been usually regular with my periods but my eating and sleeping habits have been going down the drain, maybe that's it??? Please help, it's a small possibility but I'm scared.