I totally understand I went through this for almost 3 months. The doctors and infant and development said not to force her, other wise it becomes a game to them. so one she decides she is done if possible put what ever the food is at a height she can reach and let her pick.
buy finger foods stuff she can't make too much of a mess eating and cruising at the same time.
Also get some pediasure that will give her all the nutrience that she is missing out on. Keep an eye on her weight, as long as she isn't losing much then just keep on doing what you are doing.
Unfortunately it is a stage, and she will grow out of it. I promise it will be hard but it will be over soon.