What Causes Missed Period And Pink Vaginal Discharge While On Microgynon?

Hi I have been on the microgynon pill for 8 months now I have always taken my pill religiously and my period has always come 2-3 days before the end of the pack meaning I am already on my period on the week break. It would last 5-6 days and be normal flow. My last period however was the 9th of feb and I haven t had one since 2 days ago I thought my period was starting I had pinkish blood when I wiped but was the tiniest bit then nothing else since I have done 2 pregnancy tests and both were negative do u you know what could be causing me to miss a period please