Suzie, my sit bones are as wide as yours and that was the reason I essentially got B17. However, B17S and Team pro only 7mm wider than B17 model. But the leather is strethched in a bit different way that helps you distribute your weight on the back versus front. Maybe you do need play wiht adjusting your saddle a bit more, if you shifting around and it's not because of sliding from slippery surface, then it's definately still not in a right position. All my saddles had long nose and I liked it and thought that women's Brooks would be too short for me, but it was fine on turns and I didn't feel much difference.
Anyway, I will report my ride tomorrow.
FN