Have you tried to figure out why her ears are always back? I know some "Moody Mares" who's ears aren't always back - back issues? Chiro? Teeth? Are you sure the saddle is a proper fit, have you had it assessed by a Professional Saddler, to ensure that the saddle is not hurting her in any way? Etc, etc.
Riding with your upper body in a forward position - ahead of the verticle, is an unbalanced thing, for both you and your horse.
Think of it this way - by you riding around with your upper body, over your horses shoulders, is making your horses job that much harder...because not only are you unbalancing your horse, but you are throwing your weight onto her forehand, making the take off point more difficult, and, your horse is going around on their forehand, making your job that much harder, to ensure your horse is working off of their hind end, and light up front.
So it isn't just an appearance thing.
Jumping ahead is a world wide problem, you're not alone :) Knowing you do it, is a big step and asking how to fix it is another big step. That means you want to improve yourself, so be proud of yourself for that!
You as the rider, need to be over your horses center of gravity. Learning to work in a Functional Two Point position - getting yourself over your feet, seat under you, core activated, tall upper body, open chest, learning to stay out of your horses way, so that they can do their job - will help you to not jump ahead.
Remember, it is your horses job to jump the fence, not yours. Your job is to remain solid and functional, so that your horse can remain solid and functional. You need to help your horse, not hinder.
As you already said, you need to ride your horse, not the fence. You cannot jump that fence for your horse, that's their job, not yours. You, as the rider, need to stay over your horses center of balance, and stay out of their way - you need to ride your horses rhtyhm, you need to ride your horse and forget the fence.
Allow the fence to come to you, instead of you rushing to it. Ride the rhtyhm - ba dum, ba dum, ba dum. Functional Two Point. Ba dum, ba dum, ba dum - fence. The fence isn't there. Ride your horse, not the fence.
Easier said than done.
I recommend having someone put you on the lunge line - ask your coach. Get on the lunge line, with no reins. Figure out where you need to be, to stay functional and out of your horses way. Set up trot poles, 4 in a large circle - 20 meter, 30 meter and work on your rhythm. When a trot pole approaches - so what, continue to ride in your functional two point and just staying out of your horses way. Learn to allow your horse to come up to you, while you stay functional, and just stay there without throwing your upper body forward and throwing all of your weight on your horses fore.
Then, when you get the gyst of just staying put, move to cavaletti's and repeat the same process. Allow the cavaletti to just happen. Ride your horse.
I see this help greatly, and I do it myself, it's a great exercise and it teaches you to focus on what is under you, instead of what is infront of you.