[ABZDisney]

Have a look at the seat maps on BASOURCE website, if I had to guess your on a 777 with no First class, 48 Club World & 24 WT+ seats, shown on the site as "777 48J24W203Y"
It looks from the seat map that the route from WT into WT+ is directly in front of where the front row aisle seats at either side would be which is why there are only two on either side.
If the layout is as it shows on the seat plan then 17C looks like it would have great legroom as there's no seat in front of it.
As you say though, when you look at the BA site it shows the row in front as having three seats.
I would always tend to trust the official BA site but you never know.