i struggled with this for YEARS.
i've always been fit / skinny / lean, but the belly fat wouldn't go.
STOP doing cardio, start lifting weights, and eating lots of protein.
you need to get your muscle to fat ratio higher, then your metabolism will increase, and then you will start losing that fat.
cardio is a waste of time, this is what all the latest research is showing, and my own personal failure and recent success have only proven this.
now, HOW you lift weights is also important, focus on sets of 12 reps, and don't eat carbs past lunch.
the carbs you DO eat have to be proper grains, avoid bread [if possible, except for cheat days, which ARE allowed] - and make sure to measure your portions [it's frightening how small they are at first, but you get used to it]
and also beer, you can't drink that [because of the carbs, but because hops also give you love handles on a hormonal level]
edit: tried finding some articles to link you to, but there's just too fucking many.
google "is cardio a waste of time" or "is cardio a waste of time for fat loss", and enjoy the bevvy of results.
there's just so much to get into, heart-rate, heart-rate zones, cortisol production, immediate versus future caloric burn, etc etc etc