Just wondering what you actually weigh... probably shouldn't be asking that, sorry. I think most women are unhappy with themselves and want to be thinner when in fact they are just fine. I think maybe the first thing you should do is look at your BMI. Go to http://www.bodyweight.net/fts_bmi.html and work it out, it will tell you whether you are overweight or not.
My suggestions for loosing weight are to look at what you eat and when. For eg eat a good breakfast, a good lunch and a mini supper. Then try cutting down on your carbs and fats and upping your proteins, fruit and veg. My sister and I used to be the same weight and she has since become vegan and lost a lot of weight.... maybe thats a thought lol.