Hi! My Names Audrey! Last Month I Had A Period

Hi! My names Audrey! Last month I had a period That was on and off every 2 weeks and only blead on one side of the tampon! Now I had brown discharge 2 weeks after my last period and now I just cleaned my self with toilet paper and got a red-orange blood spot did it again and no blood, I'm sexually active have 1 kid and do not use protection or BC! I've taken a couple pregnancy tests but nothing! What's going on with my body!