I'm absolutely the same as you; that is I just have always loved to cook and have a knack for it. TWO suggestions.
One is to cook together. Be very careful; try to bear in mind that your way is not the only way. This is the hardest thing to overcome when trying to teach someone anything. But when you're doing this, don't just say, "Oh, I use about this much of that." When you're ready to add something that you normally wing it on, pour the amount you'd use on to a piece of wax paper, then have fun measureing it together. This will give her a feel for how much you are using.
BUT ... one thing all of us "cook by feel and taste" cooks CAN use is a touch of discipline. Find a recipe that looks good to both of you, and make it together. By doing this we can get an eyeball for exactly how much cumin we're putting in that chili we usually just go by taste on. You simply cannot teach instinct, but you can learn to label it a bit, and learn where your insticts come from. You can learn, yourself, why something tastes flat and needs salt or acid, learn exactly what is going on in your own brain when you cook by occaisionally using a recipe. You'll vary from the recipe, but you'll learn more about yourself and be able to put into words what you'll do different from the recipe.