Hello there Sean,
While myself and others cannot tell the composition of your body, especially your stomach, given the lack of a picture, you may be suffering from Anterior Pelvic Tilt (commonly known as "APT").
Here is an article on how to fix APT:
People with APT have protruding lower abdominal regions, despite being skinny or average. It is due to your pelvic girdle tilting forward ("anterior" is the terminology used for front in fitness). It may also make your butt look bigger because your glutes are then being pushed slightly backwards due to the back - or posterior - of your pelvic region being pushed backwards.
It is generally caused by either or a combination of muscle weakness or muscle tightness. Two popular reasons that come to mind are weak abdominal muscles or tight hip flexors.
If it is indeed fat, following a regular diet with a caloric deficit of 3,500 calories per week with the inclusion of exercise is the way to go. It is widely accepted that low carbohydrate diets work optimally for weight loss due to lower levels of Insulin, less water being retained in the body, and dietary choices when people opt for higher fat in their diets (which usually equates to a higher protein intake).