I know that I am slightly late replying ! But I have only just joined, so forgive me ?! aha.
I understand where you are coming from, I used to feel like I had a good-ish sense of style ! But, somehow I have got lost in jeans-and-a-top-land, but i feel dull and like a small child. I am turning 20 this year, and its sorta sad because my mother, who has lost a load of weight and looks really good, buys the same clothes as me, AND LOOKS MUCH BETTER ! aha. This sends me into and even deeper despair because then i don't wear the nice dresses etc, and back to the jeans I go !
I think the main issue I have is that I wonder how they all look so good in the magazines, well its photoshop, personal trainers and hours of their days spent focussing just on how to look good. I, as a student nurse, have neither the time nor money for such things !
I think its more about your thought process, you have to think good to feel good
Find something you think is nice, not what you think looks nice on HER ! because no body is the same, and clothes look different on, literally, everyone. And if it makes you feel happy and confident wear it. The chances are you don't look 16 ! Or rubbish. Or ugly. Because when you feel abit more confident that's normally the first thing people notice.
Even if you start small, with like a new coat thats a bit brighter, or a pair of wooley tights. If it makes you feel good then do it
its easier said than done, I know. But, hopefully you feel abit better about it all soon