Early period?

I am a tad concerned about my period. I have a week left until my period but it started today. I am currently taking birth control everyday on time. It's not red and is brown and I am having some cramping. My boyfriend and I had sex a couple weeks ago and we had an issue with the condom but he did not ejaculate inside me or close to me But I still can't help to be scared that I may be pregnant. I'm just concerned if this is normal or not. Please help!