I agree Pam, I've had the same problem with what I thought would be fairly straightforward shots. But your selenium/cool treatment of this image has brought out the lovely lines and textures. I really like your composition too.
I know what you mean re how hard it is to get whites white when they should be in b and w! like your composition and light. The rose does look a bit grey in places though
I think this works overall -- the one thing I responded to that hasn't yet been mentioned is that it sort of looks like it's pouting. The long lowest petal gives it a dour feel and I wonder what it would have looked like with the rose at a slightly different angle. I thought your lighting and the color tones worked well.
It was harder than I expected to get a good image with detail on this white rose. Comments if you have time or inclination.