Is what I'm doing right?

I'm 15 years,I'm athletic but I don't have a six pack. I go to the gym 2-3 time a week and I do 40-60 minutes of cardio and then do different exercises like push ups, crunches and a little weight lifting. I stopped eating fast-food, candy,chips...etc I'm only drinking water and milk. I weigh around 59kg and I'm about 165.5cm. Is what i'm doing right and what should I do more? I have a little fat on my stomach what should I do more to lose that fat. Do you have any tips for me? How many gm of proteins do i need per day?