Breakthrough Bleeding

I have been on ortho tri lo for 5 months now. The first couple of months my periods were normal. But ever since november I have been getting breakthrough bleeding about 2-3 days before my actual period is suppose to start. I know it has to be breakthrough bleeding because I am still taking the active pills when this is happening. Ive been reading up on this on the internet and there are so many mixed answers that have to do with breakthrough bleeding. I have never missed a pill in all the 5 months I have been taking it, and I take it at the exact same time every day, give or take 5 minutes at the most. I know this can be common when women first start taking the pill, but its been 5 months. I never had any early bleeding when I first started and now I am after months of use. My body feels fine in all other aspects. Because I am breakthrough bleeding does this make the pill any less effective? And, how normal is it for this to be happening after 5 months on the pill? Do I need to change my pill, or should I wait a few more months....? Im confused.