5'6", 135, F. How can I create more of a defined hip-to-waist ratio?

Weight: 135 Height: 5'6" Sex: F Age: 19 Goals: Lose fat in stomach while gaining muscle.

Whenever I get a steady workout regime going, it tends to accentuate my lanky, boyish figure and I tend to lose the little hip to waist ratio I have. I love my long legs and I have a big butt which I am quite fond of, but I hold fat in my stomach area... I do not have a super tiny waist/hourglass figure and stomach flab makes it more obvious. Are there any exercises that will help elongate my torso and burn off this stubborn fat? I enjoy yoga which I believe should help, but I was just curious if any other females have had any success with this.

I played competitive field hockey for 4 years (2006-2010) so it's quite easy for me to build back lower body muscle. Additionally, I have quit smoking as of this week (smoked 2-5 cigs a day, more when drinking).