No she is not too old to train. She is still a young dog and young dogs chew. My 10 1/2 month old will chew almost anything if not given good outlets for his energy.
One way to help increase the amount of mental stimulation she gets and give her an outlet for appropriate chewing and extra energy is to stop feeding her from a bowl and start feeding her from Kongs and other food dispensing toys. You can also set some of her daily ration aside to use as rewards for calm behavior. The stark contrast between the more work to get food from the Kongs and toys and the easy to get food from paying attention to you and being calm should help to make her more responsive to your training efforts as there will be more motivation to figure out how to get the easy food.