Its almost 2 months since i dont have my cycle when i started using daphne pill?

i started taking it last oct. 13 this year. last nov. i dont have my mens until now. but i still taking the pill. i already tried the pregnancy test and the result was negative. but why until now i dont have my menstraution? is it a side effect of daphne pill? it states in the info sheets of daphne adverse reactions that menstrual irregularities like spotting, breakthrough bleeding and prolonged periods may occur in some women. do i have to worry about it? by the end of this month, if my period will not yet occur i think i have to go to my OB. but first i want to hear your answer regarding this as soon as possible Thank you and more power