I just finished my three weeks of tri-estarylla and have been on the placebo since monday. With tri-sprintec i would just throw the placebo away, and did the same with the new meds. I usually would start my cycle on wednesday evening, and that is down to the 'T' in all my cycles. It is thursday morning and I still haven't started. There is no chance I can be pregnant, seeing as I have never had sex. What could be the cause of this?