Abbie,
Hey! I'm around your age (12) and I know what you mean. It's hard finding clothes that make you look "stylish", but make you look 10. If you're looking to spend a little bit of money, try Target, or Kohls. they have very cute and stylish clothes for less than half of the cost. If you can fit in junior sizes, I would reccommend shoping in that section too. You can find lots of good clothes there, that make you look young also. Stores to try : Old navy, hollister, Gap, Target and Kohls
<3 Sammi