She does not revert to the usual vesatot of chodesh/beinonit/haflagah because her periods are controlled by the pill. She should still observe her veset kavua of 2.5 days after her last pill, as well as the onah corresponding to her bleeding last month. For example, if she bled 3.5 days after her last pill, next month she will observe the onot of 2.5 days and 3.5 days after her last pill.

Some women don't have a specific day or onah after the last pill in which the bleeding begins, but establish a limited range of onot (up to three days) in which the bleeding may begin. Thus, for example, if the bleeding could begin any time between 2.5 days and 4 days after the last pill, that entire period would be observed as an extended onah.

Please feel free to get back to us with any further questions.