Am I just a "big girl?"?

So, I'm 5'5" and I weigh..... 140 pounds. I feel like that's A LOT. I eat really healthy, all organic, fruits and veggies, whole wheat (though I rarely eat bread), almost no cheese, no refined carbs, etc. and I consume on average 1500 calories a day. I run/elliptical/zumba for at least 30 minutes about 5 times a week. I have a lot of muscle, and my abs are pretty defined for a girl. BUT WHY DON'T I WEIGH LESS?!?