Giant Breed Puppy Food for an English Mastiff?

Currently have a 5.5month old English Mastiff. I have been feeding her Innova Large Breed Puppy Food since I got her. She has been doing great on it so far, however, now I feel like I am having to constantly supplement her food with wet for her to even look at it and even sometimes with the wet food she wont eat it all. I have read reviews at dogfoodysis.com and understand that it is a great food. Im just concerned that maybe she isn't eating as much as she should be. Should I switch brands? I have heard great things about Holistic Eagle Pack (which is only rated in the 3 category which kind of bothers me) and Solid Gold (which is a 4 I think). I would hate to downgrade her food, as when she hits 18months I will be switching to a high protein based food such as EVO. Or maybe its just her age where she doesn't want to eat as much as she once did? Unfortunately I dont really agree with my vet's choice in food recommendation (as I sort of feel she has been bought out by a company--Purina Pro Plan). Nor with the breeder's choice. Any advice?