Are you trying to bend the whole body, or ask for flexion at the pole? You can ask for flexion with the inside rein, but it's not a great tool for bending. I'm thinking maybe start with the simpler concept (for her) of flexion at the poll which will start the process of bending around your inside leg. Here's a few exercises to start with.
1. At the halt, with sufficient rein contact, just enough to feel both sides of her mouth, pick an "inside" and rotate you inside rein so that your knuckles turn upward. This is what's called an indirect rein. While rotating the rein, ever so slightly bump her with the leg on the same side. She should respond by flexing her poll just enough to where you can see her inside eyelashes and nostril. Do this on both sides for about 10 times or until you know she understands what you are looking for.
2. Same exercise at the walk. If you need something to keep her interested, weave through some cones or barrels. Just get enough flexion to see those eyelashes, straighten both reins for a step and head back to the other "inside".
3. Ride corners. Use ground poles to make corners if you don't have a confined ring. Walk straight into the corner, a step before the turn, inside rein and bump or press with inside leg to get the flexion for a balanced turn.
Once she's doing all those well, move onto circles that will engage the rest of her body. You'll have to add two additional aids to get the bend. Your outside rein will control her outside shoulder and keep her from coming off the circle. Your outside leg will slide slightly behind the girth to keep her hindquarters from swinging out. Between your outside leg and inside rein creating flexion, your horse should look like a bow, with a nice gentle curve to her. If all the pieces are in place, she will feel soft and supple.
All this is dressage stuff by the way, so if you have access to a dressage instructor, I'm sure it will help her a lot.
That's all I have for now. Hopefully others will ring in with suggestions.
You just have to see your distance...you don't have to like it.