ANSWER:

This is is sufficient for the upper part, the jilbab must be very loose, thick abaya as this ensures covering the whole body leaving no room for error. 

Is it enough that the length of khimar which is head covering cloth wearing on main loose dress,apron should be such that, it will cover head,neck,chest,shoulder, arm upto elbow? If forearms are not under khimar is it ok? Please note that forearms are already covered by sleeves of main loose dress & other necessary body parts are covered by main loose dress.