9 months old German Shepherd and still mouthing/biting

by Doug
(Wisconsin)

My shepard is 9 months old and she still wants to mouth or bite as it hurts when she does this, sometimes leaving bruises on my arms.

Is this normal and how long before she will stop this?

We have tried bark busters Bah Bah and squirt bottle and this isn't working. Our niece said shes a biter and she will never stop this.

Any ideas or help will be of great value to me. Thanks Doug