What Could Be The Reason For Delay In Periods And Sore Breasts?

Hi

I have my period on 24 november. I stop taking ginette 84 on 8th december (middle of pack) and have bleeding from 11th for 5 days. Took levonelle on 21st december as unportected sex. Have my period 22nd december for 8 days. Lots of bleding. It is 27th january and i have not have my period yet. Took 4 pregnancy test and all negative. Took two 6 days after period due and still negative pregnancy test but no period yet. Have been feeling sore breasts but no pain just a little bit. How long should I wait for my period? If test was negative (home test) clearblue should i re test? It is because of contraceptive pill ? Or it is effect of levonelle that i dont have my period?