I would be going back to GP and demanding a referal to a Pead, also consult with a dietican. If she has aversions to textures then an OT and Speech pathologist can help.

If is not enough for her to have 400mls of milk only in a day and does not give her nutrition apart from calcium and a small amount of some other vitamins. Until you see a pead I suggest trying a toddler forumla or childrens sustagen (i do not agree with toddler formulas but in your case it is a good thing to try as will get some vitamins)

Good luck xoxo