Could Taking Microgynon Cause Irregular Menstrual Cycle?

I was precribed microgynon pill 5 month ago but I never took them until now.I started taking the microgynon 30 pill 6 days after my period. So I took it for 8 days before having unprotected sex. Am on my 24 days of taking the pills.My breast is so sore for two weeks and my body feel my period is coming in the past three days. My period have been regular before I start taking the pills.I have missed my period date yesterday and am worry of pregancy and am going to get a pregancy test soon. I would like to see my period but do not know when I can have a 7 days break for taking the pills.I read the micrognon leaflets it still unclear when to have a 7 days break if you start taking the pills any other day from your first period. Please can I have some advice.