I had sex and the condom broke. He doesn't know if cummed. I took plan be just in case like 9 or 10 hours after the sex. I felt nuasea for a week and spotted for a day. Two weeks later, when I was supposed to have my period, I spotted. Does this mean I'm pregnant or is it my period ?

First of course no plan B is not 100 percent, But the sooner taken the better the percentage.

Next it can and often does have effects on your period for a month or two. One of the side effects.