K.D.
Try an afternoon snack. I have noticed that my kids are AWFUL if it is getting to be a while between meals. A piece of fruit, a cheese stick -- something light and small that will give her a little boost to get her through to dinner.
And there don't have to be terrible twos, threes, fours. They aren't terrible, they are children pushing boundaries trying to figure out what is acceptable as they grow older. Set the boundaries, set the consequenses, make sure she understands what they are, then enforce them.