Also, she will be less able to perceive you as caring if you engage in such battles. Eating and weight gain are her responsibility. Constructing communication is very important. Don't isolate yourself. A support group or psychotherapy can help you deal with yourself in relation to the person with eating disorder.
Recovery is a process.
The duration varies depending upon the individual and circumstances. Be kind to yourself. It's best to know what you plan to eat before you walk in the restaurant. Items made with eggs and whole milk cheeses.