I have a perma-gut. why?

im a female in my mid-twenties who is about 5'8" and 132 lbs. supposedly im in a good bmi standing, but i look like a beach-ball on a pike. (all the fat goes to the middle) this has been an issue for me ever since i was a little kid and even as an underweight teen. im not sedentary and do not overeat. how can i change my gut to everything else ratio?