Shay, to target those areas, you will still have to gain some muscle weight, but lean muscle weight is what you want to aim for, not bulky muscle. Aerobics and longer less intense work outs are great for lean muscle. Try to stay away from short explosive workouts. Since you are already pretty small, and not heavy, focusing on raising your metabolism helps, too. More muscle raises metabolism. Workouts like ab dance videos, and small weight aerobics are great for targeting the muscles in certain areas. A good ab workout video is Zumba, we did this in class, and I definately felt it in my abs. If you can get ahold of a dance video like that, there are a bunch of ab workouts you can do yourself besides boring old crunches and situps. Small weight aerobics are similar to many of the weights workouts that people do to gain bulk muscle, except you use small weights (like 5lbs) and do more reps, which builds on the lean muscle rather than the bulky muscle.
Also, what events did you do for track? I had no idea you did track xD
As for me, I lost 5 lbs over the past 2-3 weeks! I am currently in track, and that is helping some, but I think the thing that's helping the most is Body Dynamics at school. I have that every other day, and so I get a double workout everyother day because of that and track. It's awesome! But I've been having troubles with my knee and can't do as hard of a workout because of it, but the school's trainer is having me do strengthening excersises for it every day and its feeling a bit better.