Dont know if this will help but you could try putting a sheet down on the floor, sit her on it and put some finger foods for her age around her. My daughter is 8 months now and likes to feed herself will clamp her mouth shut if I try feeding her so I have given her strips of cheese, cooked pasta, apple slices, banana cut into strips, rice cakes (organix do some raspberry or pumpkin ones). I found that she plays finds the food and shoves it in her mouth, and theres no battle. Plus after a week of this she started going in the highchair to eat. If it works, there will be mess but anything is worth a try and you might get lucky and find something she likes which may encourage her to try other stuff.