Am I Pregnant?!

Okay so I started birth control 3 days ago. I had sex the day I started the pill and we didn't use a condom. He came on my stomach but I had to stand up to get a rag to wipe it off. I'm kinda stressing that I might be pregnant bc I heard that if cum gets any where around the vagina there is a possibility. Can I get some feed back? I'm only 17 (soon to be 18) and kinda freakin out /: