I'm thinking the B17 "N" would be too narrow for just about ANY woman. The regular width B17 would probably fit you great. I have the B17"S" which is slightly wider for women, and it's really too narrow for me.
Your hips are not narrower than most GUY's hips, are they? If they are not, then you should opt for the regular B17. You want your sitbones to rest WITHIN the saddle metal frame edges, not directly ON the frame edge. If your bones sit ON the frame edge, they will not be able to create the leather indents that makes these Brooks saddles so comfortable for your individual butt once they are broken in.
If you apply lots of Proof-Hide (order it along with your Brooks saddle) in the first weeks, it shouldn't take long to break it in to the point where it's comfortable. And as Knot mentioned, you can return it.