I would think an A chord would give you similar problems, or are you using the index to barre all three strings? I'd say a C chord is easier for me than an A.

The C chord is not one of the easiest because it spans 3 frets, though my fingers are fairly happy with it. I've always struggled with the B7 chord and the fretted B, both of which sound lousy most of the time. Devin's version of The Carter Family's Wildwood Flower is a great tune for C practice.

It's interesting that you like a wider neck because your hands are small. It sounds counter-intuitive. But there are other factors at play, like the width of your fingers and how you like to fret. Then there are the points i mentioned to Susan regarding string spacing, neck profile etc.

Yes, a d18 would be 1 3/4, as is my Eastman E1d. But I recall you had a yamaha before which may have been 1 11/16. My FS (folk small) has 10mm string spacing, whereas the FG (folk guitar) has 11mm string spacing. This is also going to make a difference, even if the nut width is the same.

Another thing to factor in is the depth of the neck. So a fatter neck will require more to clasp your hand around regardless of the nut width. And then there is the different neck shapes: U shape, C shape and V shape, though i'm pretty sure that C-shape is the standard for most acoustics these days.