you can get 179 and 189. i rode last years 179s and they are sick in deep snow but just feel way too heavy on anything else. by the way mine are for sale.
if you're that small and you're only 13 years old, there's no reason for you to get anything bigger than an all mountain park ski. check out the salomon foil in a 157ish. those should work out alot better for you.
yea i made the mistake of not telling the dude at the ski shop where to mount them, so naturally he mounted them mid sole. that's why i'm selling them. i'm probably gonna get the 189 seths this year and get them mounted +5