Dianette Pill, periods suddenly stopped?

I have been taking dianette for almost a year, and the last 2 months my period seems to have suddenly stopped. I took it before that with no problem, regular as clockwork and had my period bang on time. There is not a chance I am pregnant, but the leaflet says to consult a doctor if your period stops whilst taking dianette. Usually when something says consult a doctor it is nothing so I don't want to waste any of my doctors time but I am curious of why this has suddenly happened. Any help?