Hi,
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Since your periods are irregular, it is difficult to predict when you will have your next periods. If you were having irregular period before getting started on the hormonal birth control pills, then it is likely that they will go back to being irregular after you stop the birth control pill use. Few women also experience irregularities in periods after stopping with the hormonal pill use. One way could be to check your cervix position (it might be difficult for you to correctly assess the position at beginning). If it is coming down and if the cervical os (mouth) is feeling open, it would suggest that your periods might start within next 2-3 days time (however, this can be followed with practice and experience over time). Visit your doctor/gynecologist for further clarification and assistance.
Take care.