I don't know how closely you are trying to adhere to the source material, but here's what I see:
The white background is throwing off your color balance. Try changing it to medium gray or something similar. There's a thread in the General Discussion forum that has some good suggestions for background colors.
The source images have more of a teardrop shape than your pixels. The dark outline and round shape make your image look more like a pool of fire rather than a streaking fireball.
I think you could increase the contrast between the colors. I did a quick edit and only adjusted the colors. Probably also needs more of the dark red color throughout rather than just on the edge.
Hope this helps,
Tourist