cerazette pill confusion!!!

i have been taking the cerazette pill for around 2 years now, i rarely ever have periods on it, the last time i had one was around a year ago, however i ran out of my pill about 5 days ago and havent had chance to get any more, i havent had sex in over a month so my worry is not to do with the time in which i havent taken my pill, is it unusual to have not had some form of bleeding having missed 4 pills? i have got myself worked up enough to believe i am pregnant and need some info!