Flowers are one of the most common subjects in photography (indeed my own gallery contains quite a number of them) -- and with good reason! They're beautiful, available, and never balk at having a camera pointed at them. They do have a downside, though: because of their ubiquity, creating a floral photo that really stands out is nearly an impossible task. Does this mean you shouldn't shoot them? Of course not! But do be aware that it's difficult to get useful critique or popularity on them. Using #GimmeFeedback for this is a great idea though.
You asked about negative space, and I would definitely say there is not too much. It might not even hurt to have more. But I think the one thing that works against this image most is composition. First (at the risk of raising the ire of other artists), consider a 4:3 aspect ratio. It makes composition more natural (in my opinion). But more importantly look at the placement of important elements. For me, these are the stamen and the pistil. The stamen actually land where I would expect them to be. But the pistil bothers me. To improve, consider rotating the camera to place the stamen at the upper left third and the end of the pistil at the bottom right third. This may not work out, but it'll give you something to work from. My only other recommendation would be to soften and broadent the lighting. The direction of the light seems good to me. Just a bit harsh. If you have used any color corrections (especially saturation), be careful not to overdo it; the colors seem to be clipped slightly in the blues and yellows.
Overall, this is still a very good image. Keep at it!
I agree on the whole with aaron (eagle79) especially about the composition with one of the key flower element (pistol?)almost hanging off the bottom of the picture! This brought up in composing a similar image into a key section of the image would really draw the eye in and not out of the picture!
What aaron thinks shows harsh light i agree. A softer diffusion of the light source (with tissue paper/a proper bought diffuser/some white muslin or other similar white thin material) would really benefit the picture.