Am I pregnant?

Hi everyone,

I’m 16 yo and I’ve been in a relationship with my boyfriend for 9 months now. We were on a biking trip and we did like 100km every day and one night we had unprotected sex for like 20 seconds but he didn’t cum in me or anything and that was 2 days before my period. Then I had my period but it was lighter than my usual flow and it was brown but I had a big cloth and bad cramps. I was still biking tho so I don’t know if physical effort can mess with your period. What do y’all think? Like could I be pregnant?