How to encourage my child to eat well? On good days she can eats like 2 full meals but on bad days, she refuses to eat anything.

Give your child control of the meal to a certain extent. You can let her help you prepare her own meal, or let her choose the ingredients for her meals. Children are attracted to cute and colourful things. Make your child's dinner attractive, or make use of interesting cutlery like those from Constructive Eating. Shape food into faces or things she likes. You can look up bento blogs for inspiration. http://sg.theasianparent.com/help-for-parents-of-picky-eaters/