Weird period

About 5 days ago my SO and I had sex but the condom broke without us knowing (usually we can feel or hear it break but this time we didn't know until he started to cum and pulled out ). I took an ECP  within an hour of us having sex and today I got my period (it was supposed to be due today anyway) but it is lighter than usual but too heavy to be spotting, could this be due to me taking the pill? TIA