What I have learned is that modeling is advertising, and where there is a product there is a model in need, therefore models are of all types but it is important for an aspiring model to market herself in the right ways. Think about it everything from sponges to furniture, computers, cell phones, haircare, shoes, tampon commercials! So much out there needs a model. So your perspective of what modeling is can help you as well. Think of advertising, keep advertising in mind and it will help you see where models of all heights are used. High fashion is not everything.
P.s: If you are looking for a modeling agency don't look for a "petite" modeling agency, focus on getting with a print agency because "petite" modeling agencies do not exist... yet.