In order to see your flat belly and abs you need to get rid of any layers of fat ontop of the muscle. You can do as many crunches and ab exercises as you'd like and they will indeed help the muscle tone but not the fat. What you should do is cardio to blast fat along with ab exercises. There are beginner cardio workouts on this app. Juat browser around. :) Also do 100 squats 3 times a week.

Im 5'7"

I love your height and your weight and yes u are done growing sweethart