Well, i beleive a tiny waist can make you look small, but there is nothing you can do about it. Its all genetic. I have a 34 inch waist and i dont have any fat on my stomach at all... I have big hips and a wide waist.
It does make me look alot bigger when i wear a tshirt or even a button up... It sort of makes me look wide but when the shirt comes off the wider waist line makes me look wider in general.
I guess you could do some weighted sit ups to get some thickness in the midsection... thats what i did, mine got really thick and so did my abs, i think it looks alot better