How do I get a flatter stomach fast?

Im 15. 5’3. 115 pounds. And a guy. I have six pack abs and they show good when i flex. they partially show when not flexing. I run about an hour a day. and do ab exercising like 30 minutes. I have hard abs. I am not skinny. And im not fat. My stomach looks big and fat but thats because of my big hard abs underneath a thin layer of fat. And having a hard six pack with the layer of fat makes my stomach big. What are some exercises i can do to tighten my stomach, loose fat around my stomach. I drink atleast 2 liters of water a day. I have a good amount of muscle everywhere (arms, legs, abs, etc.). But i mostly get collect fat on my stomach. My doctor says guys usually collect most of their fat near their stomach.