No, I don't think it's possible to lose your talent.
I'm going to be honest sweetsabrie. When you were writing short stories as a little girl, those stories most likely sucked. As someone who's older and who's writing skill has developed, you're beginning to see how much practice you still need to become a good writer. Do not judge how "good" you supposedly were way back when. Most likely you weren't good at all. Let's face, unless you're a child genius, you weren't writing great things at a young age. Go back and read some of your writing when you were younger and you'll see how much it sucked.
The good thing, though, is that you're able to recognize that your writing needs improvement. This means you can improve. People who can't recognize bad writing from good are the ones who are going to stay in the habit of obliviously writing crap. So, practice. The more you practice and research basic creative writing the better you'll get. You need time, patience, and practice. Forget how great your friends and parents and siblings told you your writing was when you were a wee child. It wasn't great and you'll do much better now, as an older teen, than you ever could as a child. Just get back into the habit, read as much as you can, write as much as you can and you'll begin improving.
Lastly, just like you can't become some great painter or guitar player overnight, you can't become a great writer overnight. It takes time, and for most people, it takes years. You're only demoralizing yourself if you think you're going to start writing something great right now. You're not. It'll take years of practice and studying. Most of your favorite authors were writing crap, but they kept writing and honing their skill and that's how they became better. GL.