I personally wouldn't make what she eats a big power struggle. What they eat is one of the few areas kids are in control of. What they get served to eat is what parents can control. I don't think it's an area where the parent needs to be the boss. That's a good way to cause food issues down the road.
Being picky is totally normal. I have a picky eater myself. At any given time, there are probably about 5 different foods she's willing to eat. It's frustrating, but I don't make a big deal about it. I offer her the foods I know she'll eat in as healthy a version as possible. For instance, we are pulling out of a bagel and cream cheese phase. She was asking for them all day long. So I only offered her the 100% whole wheat mini bagels with a little cream cheese. I also continually offer new foods. Sometimes she tries them and spits them out. But, at least she is getting exposed to them. Sometimes she changes her mind.
The stuff your daughter is eating doesn't sound that bad even though it's limited. I've been able to slip extra fruits into my daughter by making smoothies and freezing them into popsicles which she loves to eat. (We often do an OJ, strawberry, blueberry, banana, peach mix. We use frozen fruits instead of adding ice.) You could offer her whole grain or spelt noodles (they're more mild tasting than whole grain noodles) to get in more fiber since she doesn't eat many fruits and veggies. My daughter will often go days without touching a vegetable despite being offered them all the time. There is a book called The Sneaky Chef by Missy Lapine which tells you how to make purees and hide them in food like another poster suggested. I've been trying out recipes once in a while. So that's another option. I'd still offer the real thing on the side though. You could cut back on the milk a little to see if she'll eat more too.
I don't supplement with pediasure or anything else since I avoid stuff with corn syrup in it. I also offer her a Dr. Sears brand multivitamin which doesn't have the corn syrup, dyes, or other bad stuff in it. And she's just fine. Her weight has always been ok and she's always met all her milestones. If your daughter is not underweight, I wouldn't worry too much. Usually, there is one meal my daughter eats a lot at and the other two she kind of grazes or eats a small portion at.
Finally, the teething (and she could have cold symptoms because of the teething) could DEFINITELY be affecting how much she eats. My daughter would sometimes barely eat anything while cutting teeth. Then once the teeth were through, her appetite went way up. So I'd hang in there a little bit until her teeth come in. Maybe she'll eat more popsicles because they'll feel good. Hang in there.
