I am riding in a curbed kimberwick, but my mare wont lower her head...should i switch to a pelham?

She is 4, yes I know she is young, but she has worked through that snaffle in a matter of months. She has been riding for merely 7 months (after being pastured when she was auctioned) and she has not competed successfully at Pin Oak levels 0-3. The only problem is on flat, she is TERRIBLE with her head...she looks like a giraffe. Any types of bits would be well worth my time. I am willing to try anything that is mild to nice on her mouth.