I had the identical situation with my oldest. Once I introduced him to those blasted Gerber snacks (wagon wheels, puffs etc.), that's all she wrote. No more anything to eat but those. It was like he was addicted! If I didn't give them to him, he would have an awful tantrum. This combined with Grandma's feeding him sweet rolls and donuts turned into a Carb nightmare.
My solution to the problem was to wean him. Long before "The Sneaky Chef" and "Deceptively Delicious" (by the way I highly recommend both cookbooks available at amazon.com) came along, I started hiding veggies, fruits and meats in bread based foods such as muffins, breads, pies etc. Except, instead of using processed flours and mixes, I started grinding my own whole wheat organic flour. On lazy days, I'd use already milled stuff from the organic grocery store. I used no sugars, and would substitute organic fruit juices to sweeten things. Before I knew it, he slowly kicked the "fake" food cravings and actually eats very healthy now. And not just "breads and carbs". He eats veggies..and fruit! :)
I don't allow very many processed snacks in the house now. And with all subsequent children, have totally avoided all of those snacks, meals, etc. aimed at toddlers. That stuff teaches bad eating habits, and is probably not very healthy. I don't know for sure...but I'm basing this on my own experience. Go organic, I swear by it.
And about the snacks...forget them. If your child is gaining weight, and seems content, you don't need them. Forcing your child to eat when they don't want to IMO only invites eating disorders. Let her call the shots. All we can really do as parents is make sure the food they're getting is healthy and safe and that they're eating something every day. Even if its a small amount.
However, don't discount mother's intuition. If you think your daughter has a problem that's causing her not to eat, definitely see her pediatrician. But as I said before, if she's eating, she's fine. In fact, my pediatrician never blinked an eye when I came to her concerned because the puff-eater was only eating puffs. She said introduce healthier foods, but don't force him. She said no kid will ever let himself starve. They will eventually eat. Even if it takes a while. She recommended a very loose feeding schedule. Check out the Superbaby Superfoods book. The chart inside is what she recommended to follow as a guideline.