Good health really does some in many different shapes and sizes. I'm roughly 5ft5" tall. I weigh around 145 pounds. Some people might think that's fat. If you were to look at me, you would say that. Many people tell me how skinny I am. LOL !! I'm pretty fit and exercise regularly. As a result of my increased lean muscle, I am densely packed and look small. But, I weigh more because of that lean muscle.
If you are an active young woman, you probably have more lean muscle than you think. Which is why I too am going to encourage you to have your body fat percentage checked. Have a personal trainer do a 9 point caliper test. Don't let them use a body fat scale or those hand held monitors. they are notoriously inaccurate. Make them use the calipers. They'll take measurements at 9 points on your body. those readings will then by plugged into equations and the results will be your body fat.
at 145 pounds, my body fat was measured at 16%. Would you call some with 16% body fat overweight ?
This is why you can't beat yourself up if you don't weigh a particular number. someone who's 5ft 5" is very different from another person who's 5ft 5". Check out this website. You'll see how different women's bodies can be. www.mybodygallery.com/search.html?height=5