We went in January with our then DD6 and then DD2. Kids under 3 don't get any credits. I don't think that I ever bought anything (with cash or dining plan credits) for DD2 except large milk bottles from the general store at our resort using snack credits (hint: the milk bottles at the general stores are larger than the ones in the food courts, and, if you are at a deluxe or mod, you can store them in your fridge!).
I brought small cereal boxes and snack food (gold fish, nuts, raisins, etc.), which supplemented my 2 yo's meals. She isn't a big eater.
Many of the TS restaurants are buffet, and you can just get a plate for your 2 yo. Even at CRT, which isn't buffet, they provide a plate of food for the under 3 crowd. At other TS restaurants, there was so much food that we just shared. Many of them have bread. Many times, they provided a drink for our 2 yo for free. Or I would order a drink for her since I mostly drink water (or wine, which isn't on the dining plan). Or we would bring a sippy cup with milk (disposable sippy cups are GREAT!) from the resort to the TS restaurant. Sometimes, I would have my DD6 share her kid's meal with DD2 with the promise that DD6 could share my dessert. And then I could also talk DD6 into choosing the fruit for dessert for her kid's meal.
We would get breakfast from the food court some mornings, and, if you get the huge adult breakfast, it is so much food that you can share with your 2 yo (or even with both kids!). I would get the huge adult breakfast meal for DH and give the pancakes to DD2.
Another helpful hint that I didn't figure out until about halfway through the week is that you can ask for fruit instead of dessert at CS (if they have it at the CS places). Since we were having dessert at our TS meals anyway and they were better desserts than at the CS restaurants, I started asking for fruit and then I could give some to my DD2.
If your 2 yo is a big eater, you can always buy a kid's meal out of pocket.
I don't think that my DD2 ate so well nutritionally (but then neither did DD6 for that matter), but she never complained about being hungry.
Most TS kid's meals can be tailored to the child. We are vegetarian, and I could even get some form of "grilled cheese" at most CS places even if it wasn't on the menu.
Have a great trip!