Advice

So I'd like so input. I need to know exactly how worried I should be. So, I had sex with my boyfriend. We used a condom and we made sure that he pulled and came in the condom. I am not on birth control. I am an overthinker and stresser. I know I should be fine but my period is 4 days away and I'm just not feeling the topical symptoms I usually do? I just don't know. Has anyone gotten pregnant this way? What do you think the likelihood of this happening is?