Touch the Sun

You're kind of on to something to this idea, but chances are we could have executed this and create something a lot more exciting.

They say that using your empty space well is just as important as the shapes your subjects create. Putting Celestia in the center might not be the best place, but if you have ever heard of rule of thirds, you should know that plenty of great art is not really symmetrical. The shape which Celestia is making on this piece is not symmetrical so we are probably better off not putting Celestia center while having a lot of negative space around. This doesn't feel focused enough, at least to me. There might be a way to cut out the extra space and creating something more exciting instantly.

Plus, another idea worth considering... Celestia's body is vertically aligned. What if we have it diagonally aligned instead? Diagonals are more energetic than verticals. Celestia being pretty vertical suggests that she's just flying upwards. If she is flying diagonally, you should get a stronger sense of moving somewhere, and perhaps something more exciting in the end.

Congrats on not tracing an image of Celestia, but people tend to say that people need references to avoid making silly mistakes and to be more familiar with what they're drawing. Celestia's body proportions appear closer to Luna's own proportions. If you look at this long enough, you'll notice that her legs have different proportions. One back leg is slightly bigger the other. Individual sections of her front legs are differently sized from the same section of the other front leg. To me, it's a curious observation, but what's far more important is coming up with a more interesting way to frame your subject and a more interesting way of drawing Celestia (i.e. not vertical).

Should be something worth considering so you get more than just decent, but something that makes you go wow!