Almost done with sugar pills but still no period. pregnancy test-negative. what wrong? im worried

Possibly nothing: Sometimes menses may not occur with a cycle of oral contraceptive pills. This is not unusual if the pills have been taken for some time. It is due to thinning of the uterine lining. If it continues and remains disturbing, then the pill brand can be changed. A pregnancy test is a week may provide additional reassurance. The pills should be continued.