125 is probably achievable for a woman your height. It's hard to say if you could carry enough muscle mass to look muscular at that weight. Is that really what you want, or are you thinking more of the smooth, slightly bony look of a Victoria's Secret model? For an idea of what different amounts of muscle look like on a woman about your size, check out Meet Staci: Your New Powerlifting Super Hero | Nerd Fitness
You know, I love my scale. I get on that baby every single morning. But when I look in the mirror, I can see very clearly that just losing what looks like 10 lbs of fat around my middle is not going to give me a body that looks amazing in a swim suit. And losing another 10 lbs beyond that isn't going to do it either. The only thing that's going to give me the look I want is some serious strength training. And that's going to add pounds, not remove them. So if you want a muscular body, I think you need to love the mirror more than the scale.
CW-125, part calorie counting, part transition to primal
GW- Goals are no longer weight-related