Talk to Gynecologist on Irregular Period

As salam o aleikum My sister had her periods on january 23 for 7 days Then next periods 4 March ko hue Then 6 April then 16 may June 23 , july me priods nhi hue then 17 August ko abhi periods ki konsi date hogi Aur cycle days kya hein , periods late hony ki kya waja hai Meri Sister married hai aur 3 years ka ek beta hai