First thing to think about is whether your abs are developed (I guess you are training core-abs&lower back as well as the other muscle groups), and if you have a low body fat % (like 10%), you should have abs pretty much visible. Now not every body is the same, but for most people fat stores the most on the thighs, stomach and chest area, and basically since it stores there the most, it's gonna take a lot more time to lose it there,than lets say the arms & back, which is why you might have other parts developed than the stomach. I can't see how much fat you actually have, but, in order to lose fat, you need to be in a calorie deficit at the end of the day, week, month and so on. Fat isn't going to magically turn into muscle, they are separate cells/tissues (whatever you want to call them), so you actually have to burn the fat. And as you get leaner, it's harder (but not impossible) to burn the fat off, so you need to up your protein intake while eating in a caloric deficit (burn more calories than you consume), maybe do carb cycling- it has been known effective for people struggling to lose the last few kilos (eat more carbs on workout days, and less carbs on rest days, even though carbs are very important, first to restore the glycogen after the workout, but also for energy source, and especially as a teenager, don't go on a low carb, + that you will eat in a calorie deficit you will have even less energy if you cut out carbs so be careful). Some also do fasted cardio or fasted training (where you wake up and train in the morning without any food in you), but I don't know how good that is for your muscle, some people prefer it, others don't because it kills both muscle & fat, I think if you do very high intensity for too long you will lose some muscle, but I don't know if it has any benefits of burning more fat-calories since you don't have any food-calories in your system. In the end, you can literally lose fat without C from Cardio, if you limit your intake, and it is hard, especially the first week, now you probably know this and probably do it: eating less junk food, less added sugar and so on. In this case you would need some cardio I'd say, so start doing something like running, jump rope, cycling, swimming. And don't be upset if you don't lose it in the upcoming month or anything like that, it takes time! Good luck! :)