Hi.i Am Using Pills For Almost 1yr.but Then I Observed

hi.i am using pills for almost 1yr.but then i observed that my face started to be oily & have pimple/acne..so i consult to my ob to change my pills & my ob prescribe the althea pills.but as my pb advised i need to wait first my nxt menstruation bfor i can able to start althea..but it suposed to be last december 4....but till now i havent yet my menstruation period....i already take twice p.t. & the result is negative so i try to start my althea the first tablet.but i admit it so scary for me...i dont know if its correct for me to do such decision what should i do?