Question Summary:
I am confused about my monthly periods.

Question Detail:

My question is regarding periods. Earlier my habit was seven days but after delivery it changed to ten days.  But again after my third baby, it became seven or ten days.  One month I get for 10 days and for another 2 or 3 months it goes for 7 days. 
This month it was for seven days.  The 8th day there was no bleeding.  On the 9th day, a spot was seen.  However, after that no blood was seen the whole day.  I am confused.  Should I start praying on the 8th day or should I wait till 10 days.

Answer :

In the Name of Allah, the Most Gracious, the Most Merciful.
As-salāmu ‘alaykum wa-rahmatullāhi wa-barakātuh. 
Your periods will be right until the 9^th day when you had the spotting. [1]   After that take a Ghusl and resume your Salāh.  Since your bleeding cycle changes, you should apply your discretion and decide upon that.  If you are certain that the bleeding will resume after the spotting, you may delay your Ghusl.  If there was no bleeding, then you should make Qadhā of the missed Salāh.  
And Allah Ta’āla Knows Best
Mawlana Abdul Azīm bin Abdur Rahman,
Student Darul Iftaa
US
Checked and Approved by,
Mufti Ebrahim Desai.
www.daruliftaa.net