Using a reference will help you with proportions and shapes :) your fairy is AMAZING, I wish I could draw wings like those, and I love your background. Especially those rocks! Horses are really hard to learn to draw, nearly as hard as people, so really studying their anatomy and proportions will help a lot.
I don't want to hijack you but just to show you how much of a difference it makes, this is me unreferenced: Cramond K by =2close2dasun on deviantART
And with a ref, drawn in Photoshop with my graphics tablet: Lumin Ref and WIP by =2close2dasun on deviantART
My unreffed work isn't BAD but it's not as realistic as when I use a reference. And if you can't find a ref that fits, you can combine two. It's easier with photoshop though, because you can cut the head from one horse and slap it onto the body of another [which is what I did with this: Lucifer 2013 by =2close2dasun on deviantART
] rather than having to attempt to fit the two together in your mind.
The point in showing you these? To give you hope, because THIS was me 4 years ago: P R I M A L ::redesign:: by =2close2dasun on deviantART
And I don't have any of my REALLY embarrassing stuff on that deviantart account, there's some on my old dA though: Dreams by ~ImmortalShande on deviantART