Breakthrough bleeding, sign of pregnancy?

I am on birth control, combination pills to be exact and I have been on it for over a year now. I haven’t missed a pill, sometimes I have taken it a couple hours late though. I am sexually active with my boyfriend and we use a condom every time we have sex for extra protection on top of the pill. I had a very light period in March that only lasted a day so I was a little confused and got anxious that I could be pregnant even though I know the chance is very small so I took a test a week later which came back negative. I am now on my second week of active pills, two weeks away from my period but I am bleeding as if I were on my period? It started yesterday and I still have it, it is bright red blood (TMI sorry) and normal/medium flow with some back aches and cramps. This isn’t a sign or pregnancy right? I haven’t had any symptoms or anything of pregnancy... I understand this may be a sign that I need to change my pill but I just want to make sure I am not pregnant. I am not looking to be pregnant right now... thanks ladies!