Could it happen??

Ok so I have a question ladies, my husband and I had sex 4 days before my expected period. We used a condom, but somehow it got stuck inside of me. Now before you ask no I’m not on the pill due to birth control makes my blood pressure dangerously high for some reason. Now, when he pulled it out it barely had any cum in it. I’m freaking out! What would be your opinion? Is it possible I could become pregnant with a 31 day cycle? This was on the 19th and my period is due tomorrow... Ive herd of it happening to women before..