sex and placebo pill

Just wondering about sex before your period. I was on my first placebo pill and my bf and I had sex. We didn't use a condom but he did not come inside me as he pulled out. I got my period for 1 and a half days, it stopped for about a day then started again for another two. Just wondering if anyone knows if that's normal? This has never happened with my period before. Ive been on the pill for almost a year and a half now. If someone could help Thank you.