Why enter Motorway at Kot Abdul Malik? You know that there is kinda loads of traffic near that place?
Easiest is and the one I usually prefer- FSD to Sheikhupura via GT road. I go straight at the first roundabout ( The one before the Jungle ) and I enter Motorway.
Then I take the first Lahore exit and enter GT road towards Islamabad.
Much easier, not sure if you checked the Route, here it is again.
http://goo.gl/AzDWs2