i had been on yasmin for over 5 to 6 years and just changed to yaz at the being of this month i should have gotten my period during the week on christmas (should have started christmas eve) either birth control would have had me starting on that day. i am sexual active and always use a condom. i had some small bleeding (that was red and brown) the dec. 18-21. and it stopped the 22. i took a pergnancy test and it was negative. i need to know if it is normal to not have a period the 1st month of changing? if you know anything that would be helpful