I'm going to post my honest opinion about this.
First word that pops into my head, Op. Your character is very overpowered and seems to only have one weakness (which I'll get to in a minute). She also has "no friends" and no family, which would probably cause extreme depression. I know if I had no friends or family, I would be in a mental hospital.
Now, her weakness. With a weakness like that, your pony would be dead the minute she was created. I can tell you that there were at least ten fires put out in the last minute around the world.
Can grow wings and horn at any time? I don't have much to say.
I find "evil forms" are way overused and can be classified as a sort of mary-sueish/gary-sueish quality.
That's all I have.
The art is good, but like Princess Nightingale said, use the circles.
Keep going! ^-^