It's all apart of growing up! Your tastes change (as do size, height, etc), but it's even more of problem when you've become old enough that you can't just go out and have your parents buy you new things. So, my advice to you is this-- make your own clothes to your style! Or, somehow change the ones you do own into something you wear. Not really into that old t-shirt? Is it somehow more appealing if you shred it up and turn it into a scarf? Be creative! There are many how-to's online that detail how to re-vamp your wardrobe with little to no cost.
I had that problem today! I seriously have only three or four shirts I wear in public... That's mostly because after losing 60lbs, the majority of my clothes don't fit anymore and I can't quite afford a new wardrobe, so between clothes I've sewn down and new shirts, and then the few I like, it's not always a good sign.
I can't really afford much either, and I'm pretty stingy with my money as it is, but the majority of my wardrobe is either flannel, button-downs, or polos, and when you wear one after the other it's like "I just wore that outfit the other day, I want something different"... And there's nothing there... Might be time to start buying some tees, lol.
You are asking what I'm thinking. Every half year I go threw all my clothes and see that I'm disappointed with what I have in front of me. I just don't want to wear them anymore and find myself saying well maybe on a Saturday...