We have similar issues and I keep an eye out to be sure she is getting adequate protein. My daughter likes refried beans, hardboiled eggs, cashews, sunflower seeds, and Morningstar Farms "chikn" nuggets. She will also eat ground beef and oddly - boneless pork chops. So basically no bones, veins, skin, cartilage, etc. She also really likes Sugar Snap peas which have 2 grams of protein per cup.
I really like advise I read once that said - give up on balanced meals, give up on balanced days - go for a balanced week. I don't have any say over what she is given half of her time, on our days we make sure she has a fruit and veggies, whole grains and eats protein at one meal each day.