You have chosen a plane of focus through one anther. It doesn't work as well as it might have done without the other anther, in the foreground, which keeps attracting the eye. Choosing a larger aperture, to throw the foreground anther further out of focus, is one option.
If you don't have a diffuser, and there are no clouds, you can simply cast your shadow over it. (Change the white balance). I do that quite a lot for hand-held shots, where I need both hands on the camera. Specialist flower photographers would prefer bright overcast weather to sunny every time.
I don't dislike it. However, for example, the texture of the far petal could be appreciated if it were in reasonably sharp focus. I have the advantage that I have such a flower on my patio so I can "fill in the gaps" by direct observation.
Really enjoying the feedback. Here are a few from this morning, probably same flower. I know I should have deadheaded the low right bloom, but I'm trying to hone in on the technique.
These are both at F11. I also only used a 12mm Kenko tube vs the 20 in the OP. OP was natural sunrise, today it's overcast.
Same 50mm d lens on my d5100
No flash, F11
Diffused flash. Pumped the shadows a little to get the water drops to show better.
I like the fill flash. If you have PhotoShop, or similar software, you might like trying increasing contrast slightly and reducing the brightness quite a bit. This will bring out colour and texture more, especially in the highlights. A slightly subdued lighting can really do things for flower images. This being a pale colour anyway, there is only so much you can do. (Try it with a deep red rose, for example).
