I'm On Minastrin 24 Fe Chewable Birth Control. And Me

i'm on minastrin 24 fe chewable birth control. And me and my boyfriend had sex. It was my first time. We used a condom and i'm always on birth control. And i'm scared i'm going to get pregnant. im having some symptoms. I don't know what i should do. We had sex two weeks i was supposed to get my period, but a week after we had sex i was bleeding brown for about 3 days. Am i pregnant ? It's been 3 weeks since we had sex.