You'll be miserable if you reduce carbs but don't increase fats for ENERGY. Calorie restriction isn't necessary to lose weight, the science behind this premise is non-existent and things are much more complex than that. Things aren't as simple as calorie in = calorie out. Eat fats, as much as you want, even saturated (but not trans) but limit carb intake. Don't overdo it on protein. Exercise will do absolutely nothing for weight loss but is healthy nonetheless so good to incorporate it in your life but have fun doing it, maybe do a sport you like, join an aerobics class with other girls, etc.
I'm also 5'6 and at 140, I was TOO thin, face sunken and barely any curves, no breasts. At 150 +, I started looking more decent. Women are supposed to have more fat, more curves. Food for thought...I've been at this since 2003...