heavy on the bit
How long have you been riding? It takes some time to develop a sensitivity to the bit and how to "dialogue" with the horse. I like a forward horse, too. However, sometimes a horse runs forward in an unbalanced, "falling" sort of way, almost as if she is trying to run out from under you. Is her head in the air or does she come behind the bit and lean down on it? Both are evasive manuevers. Running out from under the rider, especially with head high and back hollow can be an indicator of discomfort from an ill fitting saddle or a sore back, or just a long ingrained habit.
You have to get her to come off the bit. And then she has to know that if she stays off the bit, she will be rewarded with soft hands and light contact. But, it is her responsibility to come off first and yours to reward immediateely.
Here's a suggestion,
Start out with very light contact, maybe even drooping reins. As you pick kup the contact, if she braces against you, then take up more contact in one rien than the other, creating a tiny feeling of bend, usually to the inside. Use the inside rein to ask for the bend and put on more, and more pressure with that rein (you can sort of vibrate the rein as you make it stronger and stronger). Do NOT release until she gives something in return, a release in the poll or better yet, a tucking of that side of the jaw inward. When she does , immediately give her a ton of release, do't worry about "throwoing her away". For awhile, your release has to be really noticeable. Then you do it all over again. When she IS on the bit, and carrying her own head and soft, remember to follow the mouth . Think of your hands as actually going through the rings of the bit itself and have the bent tops of your thumbe actually pointing at her mouth, this helps to keep a straight line from elbow, through thumbs to mouth.
The secret is in using UNEVEN rein pressure . Horses feel trapped in exactly even pressure and can brace nicely against it. To break up that brace, you need to have more asking/pressure on the inside rein than the outside. Once she gives, you must be prompt in rewarding her. The outside rein stays steady and eventually becomse kind of comforting to the horse.
In a horse that is really leaning on the bit, running right through my hands, I screw any dressage form and bend that horse right around until she gives in her mouth and her hind quarters unlock and she steps under herself. She sounds like a braced up horse and for that, one needs a lot of lateral work, bending , bending bending, ONE REIN active, one rein passive.
Wish I could show you what I mean. My explanations , when I read them, are hard to make sense of . Sorry, I do the best I can.
One thing I copy from my trainer is when I really insist the horse give to the bit and he DOES, I say, and I mean literally say, "Thank you" and this helps me remember he complied so I need to reward, NOW!