Help me boost my daughter appetite please!

Hi I hope someone can help me about my 6years old daughter .. I delivered her weighing 2.4kg she's tiny and until now that she's six , she still so thin ..and I am so dipressed about it ..she don't want to eat a lot.. is 17kg normal for her age???I also tried lot of vitamins bUt nothing helps what should I do mommy's? I wanted her to be healthy and be chubby..?? Thank youö