How many scoop should I give my 4 months old baby? Tin says 6 scoops = 180ml. Baby feed every 2hrs..

We just change baby formula from "Grow" since born till now 4 months, all of a sudden baby had diarrhea recently, brought her to clinic and doc said to change to isomil soy milk. Now she's okay and we just bought Nestle Nan Optipro 1 to see if this formula works for my baby..