The key is to make sure you are getting enough energy from fats and proteins. By going low carb you will probably be eating a wider range of healthy vegetables, meats and healthy fats compared to many other nursing mothers who may be snacking on bread, crisps and cakes. Also make sure you are drinking enough fluids. Here is a good thread from a discussion board on exactly this topic.
I know you posted a few months ago, but I thought I would reply just incase its still relevant. After having a daughter who LOVES veges, I then had my son who at a year old suddenly refused veges. It was getting so bad he would make himself throw it up if we forced him. But we kept on going trying everything we could while getting extremely frustrated (While also being told by everyone he was too small and sickly (Which he always was but got worse when he stopped eating the veges)
Lunch: pat dry chicken and cut into cubes. Lightly (!) salt and pepper. Heat a skillet over medium heat, once hot add coconut oil and fry chicken cubes until brown from all sides. Remove chicken, and add crushed garlic, curry paste and fish sauce to pan. Stir until fragrant and remaining oil in pan and curry paste are well combined. Then add coconut milk and whisk until well combined. Simmer and reduce sauce until desired consistency (1-3 minutes). Pour sauce over chicken and sprinkle with sesame seeds. Serve with baby spinach.