M.S.
Your daughter is at a lull in her growth, so she really doesn't need a whole lot of food. Also, keep in mind that a serving of food is one Tablespoon per year, so if you feed her a sandwich, her serving is 1/4 to 1/3 of the sandwich! It is very very rare for a child to starve themselves, and assuming your daughter is otherwise healthy, the best thing to do is serve her the meal and let her choose how much she does or does not eat. I recommend you STOP making alternate meals, because that will turn into a horrible habit you will regret ever starting. Ask any parent of an older child!
You can "trick" your daughter into eating by making it fun. Make pictures with her food, let her eat in front of the TV or a story, let her help you make it, give her dips for everything, etc. Also, the more you stress about it and beg her to eat, force her to eat, or otherwise draw her attention to it, the worse the problem will get.
In my house, we have a one bite rule. My kids must eat one bite of everything I serve and then they can choose how much of it they eat after that. If all they eat is one small bite of each thing, I do not try to get them to eat more... it is their choice. It is very important to allow your daughter to listen to her own body about how much she needs to eat. Otherwise, she will grow up learning to ignore her body's signals about hunger and full and will overeat.