Am I pregnant?

On August 28 I had sex for the first time.

I’m not on any form of birth control.

We only used a condom.

On August 30 I had my period.

On September 21 I had another period and I think it was early.

I was supposed to have my next period on October 26 but up to now I still haven’t got my period. I’m already 13 days late. What should I do?

Do you think I’m pregnant? Which is I think us impossible because I only had sex once which was August 28 and I already had 2 periods. What could this be?