Shop in the petite's department
You might have better luck at department store. In the US, I would start with Nordstrom, Macy's etc.
At 17 you might not need fabulous undergarments, bra & shapewear,
but many women look 100% better and I would get properly fitted for a bra - In the US, I would go to Nordstrom and not a VS for a proper fitting.
Here is a link to Oprah looking fabulous in black and white:
http://www3.pictures.stylebist.....I6XM-l.jpg
Notice:
The V - neck
draws eye up
balances her bust
The Belt -
draws the eye to narrowest part
A fitted shirt or one tucked in will do similar
The curved bottom of the shirt
so much better than straight across
creates a peplum effect - very good
The soft shirt fabric that drapes over curves beautifully & works with a belt.
The pencil skirt - knee length
Heels.
My 15 year old daughter needed a similar outfit for a music recital.
We found a 'women's fitted button down white shirt' in a petite size at Macy's.
Similar to:
http://www.jny.com/No-Iron-Eas.....efv2=White
or
http://shop.nordstrom.com/S/fo.....L_also_vie
This outfit was not too costly - she had the skirt, flats, and spent similar to the tops listed. The fitted shirt with a curved bottom on her hourglass, looked far nicer than the girls with straight cut shirt bottom or no darts but especially on an hourglass... IMHO .
About her outfit:
A women's fitted button down white shirt'
Petite sizing so fit her length-wise
V-neck - fairly deep - but scaled for petite
Fitted with darts to compliment the hourglass waist (no belt or tuck in)
Curved bottom of the shirt. (but no peplum or drapey fabric )
With this kind of shirt -
shop petites - so fits in length
Look for darts - can be easily altered for curves
fit to widest part - have it tailored to fit - no pulling buttons
Tailoring highly recommended unless perfect fit
Look for curved bottom of shirt - not straight across
Black Flare skirt (maybe A-line) - shorter length - 2-3" above the knee
Black Ballet Flats
A drapey boatneck or boatneck cowl type white top with ruching at the sides and a curved shirt bottom might work.
I'm sure other's have their own formulas for this type of wear.