What Causes A Missed Period With Weight Loss?

Hi, may I answer your health queries right now ? Please type your query here... Hi, I had sex with my bf on the 24th of June, and my period was due yesterday. We used protection tho, and the condom was spermicidal. It didn't break or anything. Also, since my last period I have lost about 6-7 pounds, and my bmi is 18.1. So what are the chances or me being pregnant, or has my period just stopped?