I’m so so scared

This is my only second time having sex and I know it only takes one time. I was stupid enough to do it without a condom but he said he pulled out and I’m sooo nervous about it just because of this calendar I know it’s all just a estimate..I didn’t take a plan b because he said he pulled out. My period is supposed to come next week I’m just soo scared. What do you guys think my chances are...😭 my nerves are through the roof