Brown discharge

So nearly two weeks ago now my boyfriend and I had sex and the condom broke 
He came inside me. 
However, I had started the pill eight days before this happened  
But now, two weeks later, I'm experiencing a light brown discharge 
What does this mean? I can't be pregnant can I? I mean it can be other things can't it? 
Please help. I'm 17 and I'm so so worried