All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.
Whether the divorce was a Sunni divorce or a Bid’i divorce, it is effective according to the view of the majority of the scholars, and this is the view that we adopt here in Islamweb.
As regards the bleeding that comes again after your menses, then if it comes back after thirteen days or more after the cessation of the previous bleeding, then it is a new menstruation, otherwise, it is bleeding outside your monthly periods.
Since you don’t know exactly, then in principle that time-period has not passed; therefore, it cannot be ruled as menses except after being certain that the minimum time-period of purity has passed between the two menstrual cycles.
For more benefit on the difference between monthly menses and bleeding outside the monthly menses, please refer to Fataawa 199375, 192925, 183343, and 154565.
For more benefit on Istihaadhah and irregular menses, please refer to Fataawa 345745, 380429, 362518, and 326818.
For more benefit on irregular menses and signs of the end of menses, please refer to Fataawa 395488, 361450, and 355546.
Allah Knows best.