Orange juice and water?

i gave my 24 week old baby a few tablespoons of orange juice a little sweetened on the advice of my doctor. i also gave her some water, but that the peadiatrician didnt say anything about. Is it ok? will this have any adverse effects on her? will the milk i gave her earlier (1 and 1/2 hours back) be curdled? also can someone please tell me how much of juice and water i am supposed to give?