Lost condom...... Late period

So on March 8th my then boyfriend and I had sex while I was on my period (not the first time I have done that) I know my cycle pretty well I think but we still used a condom. Well at some point the condom slid off and got lost inside me. I was finally able to get it out after a few stressful hours, thank goodness. But I'm concerned about me being pregnant, I know stress has a lot to do with whether or not you will start on time and I have been really stressed out about this and now that he and I are not together does not really help and I started a new job, so there are a lot of things working against me here but I'm not sure how worried I should be about this. All insight is greatly welcomed.