|gingerbop, are you small-framed? (i'm guessing, due to the gymnast thing)|
If so, try kids hennes/department stores with kids/teenage depts for coats. kids always get better brightly-coloured clothes... Debenhams kids departments are pretty good.
on which general note kids' Hennes are a marvel. i'm not that tiny and i fit into 164cm t-shirts/jumpers fine.... its vital to be mammarially challenged, though.
In fact, for the little 'uns amongst us, department stores are great, they're the only places that have decently-sized/stylish kids sections, and if yr small the 13/14yrs fits fine...