Not sure if this helps.....
I flew LHR-ORD-LHR last month and was sat in the 1st row of WT+ out and back.
On the outbound I had my boarding pass changed (due to an aircraft switch) and my seat moved from row 21 to row 18 but this was still the first row of WT+ and the aircraft had the smaller screens.
On the return the first row of WT+ was row 21 again and the aircraft had larger screens. Interestingly on both flights NCW ended at row 15.
I know there is some difference between the 3 class and 4 class 777 but I guess all ORD flights are with a 4 class.
So if you have access to the WT+ seatmap for your flight and row 18 is the first row of WT+ then it could be a small screen version.
Hope this helps
Bad Attitude