Why don't I have withdrawal bleeding while using Yaz?

During 4 days of using Yaz white placebo tablets, withdrawal bleeding should occur. Between 1 and 10 in every 100 people taking Yaz may experience amenorrhea, which is described in the "side effects" section. The absence of bleeding is problematic because, according to the documentation of the medicine, if the expected bleeding does not occur within two consecutive menstrual cycles, it may mean pregnancy and the next blister should not be started until the patient is sure that she is not pregnant. Lack of bleeding - after excluding pregnancy - may be, as I mentioned, the effect of hormones from the tablet on the endometrium of the uterus. If it persists for more than two cycles, then according to the documentation of the drug, contact with a gynecologist is indicated. However, it is difficult for me to assess whether you will propose a change of product. I enclose additional information that may be helpful: https://www.gdziepolek.pl/produkty/84769/yaz-tabletki-powlekane/apteki https://www.gdziepolek.pl/artykuly/jak-i-dlaczego-zglaszac-dzialania-niepozadane