Rachel; You've already received some productive suggestions from Asher and Nicolas, and you've reached a revelation of your own. So I don't know that I can offer much more. But here are my off-the-cuff thoughts on this image.
Colorful sunsets can elicit emotional responses from everyone. Rather like aurora borealis displays they're ephemeral, they're dazzling, and they're bigger than life. They prompt us to contemplate our smallness within the universe for just a few moments. So it's natural to try to bottle and share such a remarkable experience with a camera. (Many years ago (late 1960's?) I read a remark from a senior marketing exec at Kodak along the lines of, "Sunsets and kids account for 70% of our color film sales.".)
The problem is that such experiences don't bottle well. Like a long-opened carbonated beverage, these experiences somehow lose their fizz in the sharing, even the best such images. It's natural to wonder why and for photographers to blame their skills for such letdowns.
But the fact is that there's nothing really "wrong" with your photograph at all. It disappoints you because it's only a photograph. You cannot contain and share a human experience as broad and emotionally deep as a brilliant sunset in a little rectangle, any more than you could share the Pacific Ocean in a gallon jug. It's an experience in which you were immersed, not simply a viewer. That's why so much landscape photography, however colorful and skillfully recorded, is howlingly boring. Beholding something like the Grand Canyon is a far bigger experience than any lens could ever capture. ("You ain' got dat lens."
So your revelation may put you on track to create new types of images using such experiential scenes. One of the most significant suggestions I ever received along these lines came very casually from the mouth of a very accomplished photojournalist. He said, "Whenever I see a great landscape scene I search for something interesting to put in front of it.". That principal has served me very well for a long time.