I wouldn't worry about the actual pounds that you weigh because muscle weighs more than fat and then depending on your heritage, I believe bone mass can weigh more or less. I also wouldn't spend as much time worrying about the clothing size because someone who is 5'8 and weighs 115 lbs and is a size 7 could share her pants with someone that is 5'2 and weighs 130 lbs because of shape.
I would worry more about eating healthy and exercising. You can't change your body shape. It is what it is, but you can feel good about yourself by eating right and exercising, also, get enough sleep because that's key.
This is always something I try to remind myself of. At my skinniest (post basic training) I was very fit, had very little fat and because of my body shape was wearing a size 12. So occasionally I have to remind myself that I will probably never be in the single digits but as long as I feel good then who cares!
Riding: The art of keeping a horse between you and the ground. ~Author Unknown