Is it normal to have a belly fat at a young age, considering the fact that i am exactly at my normal weight(59kgs for 169cm)?

Your BMI is 21.1: Although your bmi is in a good range, it isn't the only expression of appropriateness of body measurement. You are 18 yo, so the amount of prepubertal fat should be minor or none. If you have an excess of carbohydrate in your diet, or don't exercise, your body (increased fat content) will tend to show fat accumulation on the face, neck and abdomen.