Fully 100% balanced is a load of bullshit, especially when it comes to pet foods. How can it be balanced when it doesn't resemble anything a dog would naturally eat? Dogs are predators, meaning they can hunt, pounce, and eat things - what part of that sounds kibbley? Iams is pretty nasty stuff, but then again, the vets recommend it because they simply don't know better. Yes, the go to college for it, but most vet schools only require one course in nutrition. And that nutrition class is paid for and sponsored by the people who make the most well-known kibbles (Science Diet, Iams, Purina, Eukanuba, etc), so they simply promote their product, not what's actually healthy. And then the vets leave after being brainwashed and start a clinic, often with the same kibble companies offering to let them sell their brand with a kickback per bag. Sick isn't it?
Ideally, the very best thing for your puppy is raw. But vets hate this, once again, because they're uninformed. I just don't tell my vet what my dogs eat because they'll tell you how healthy and wonderful your pup looks, but as soon as you mention raw, they start pointing out flaws that they didn't see before.
Other kibbles are pretty good too, but you want to focus on the high-end ones - often called "premium" brands. Orijen, Taste of the Wild, Innova EVO, Canidae, Blue Buffalo and other brands like that (go to the dog food analysis site that other people linked to and try to stay within the 5-6 star area).
I'm not sure what type of Iams she's been eating, but here's the review for Proctor & Gamble Iams ProActive Health Puppy (yes, Proctor and Gamble. The same people who make detergent, shampoos, house cleaner, baby supplies, etc.). Well, its linked at the bottom since its way too long xD
Kinda icky, right? To contrast, here's the ingredients for Chicken Soup for the Puppy Lovers' Soul (what my 3 month old is currently munching on):
Chicken, turkey, chicken meal, ocean fish meal, cracked pearled barley, whole grain brown rice, chicken fat (preserved with mixed tocopherols), white rice, oatmeal, millet, potatoes, egg product, tomato pomace, duck, salmon, flaxseed, natural chicken flavor, salmon oil (source of DHA), choline chloride, dried chicory root, kelp, carrots, peas, apples, tomatoes, blueberries, spinach, dried skim milk, cranberry powder, rosemary extract, parsley flake, yucca schidigera extract, L-carnitine, Enterococcus faecieum, Lactobacillus casei, Lactobacillus acidophilus, Saccharomyces cerevesiae fermentation solubles, dried Aspergillus oryzae fermentation extract, vitamin E supplement, iron proteinate, zinc proteinate, copper proteinate, ferrous sulfate, zinc sulfate, copper sulfate, potassium iodide, thiamine mononitrate, manganese proteinate, manganous oxide, ascorbic acid, vitamin A supplement, biotin, calcium pantothenate, manganese sulfate, sodium selenite, pyridoxine hydrochloride (vitamin B6), vitamin B12 supplement, riboflavin, vitamin D supplement, folic acid.
The first few ingredients are the most used ones, so you can definitely see a difference there. No corn, where Iams has it as the 2nd ingredient. Corn is a huge filler that isn't even digestible, not to mention the other crap they include.
Good luck picking one ^^