I've been using Marvelon BC for three months now and during January and February, my period always came on the second day of placebo week. For the month of March, I decided to not take the placebo pills altogether--which I know does not change anything since they are placebo pills. The problem is, I'm already on my second day but I still don't have my period. I have never missed a pill and I do not take any medications that could interfere with the BC. Any idea why this could be happening?