It sounds like she is retaining her puppy teeth still. This is very common Taycie had a couple sets of doubles and when I had her spayed I had the vet pull her remaining puppy teeth. Her breath was starting to smell a little fishy and once they pulled them, the smell went away immedietly.
I would also check out a different food option. I know alot of people like Royal Canin but I feel it's overpriced for what it is. There are so many wonderful natural foods out there! Many on here, I am sure, will offer suggestions.
I would check out Orijen, Acana, Nature's Variety, Taste of the Wild, Natural Balance, Wellness, Blue Buffalo, Natural Balance... to name a few.
Check these videos out they are excellent and she offers excellent advice about foods.