Cool shot and don't be worried about the fire to much, it is very hard to get any fire to look 'real' in an FS shot, I spent hours trying to get a space shuttle to look like it was on re-entry. My fire looked about the same as yours when I finished. Now that I think about it you might want to put the fire on it's own layer and assuming your using PS make a couple layers and mess around with the blending options to make it brighter etc. Also try and use filters such as glass, glow, and plastic wrap to try and give it a bit of depth. Also
www.good-tutorials.com has many great fire tutorials you could use to adapt into FS. This is all assuming of course you ever want to do another fire shot.