Don't limit your modeling abilities to only the fashion world. There are handbags, shoes, hair products, beauty products, jeans, skin care, and so much more a girl who isn't 5'10 or 5'7" can in deed model. It started from pushing yourself starting to promote you and researching and treating your modeling goals like a daily pursuit, what it can take to get in a magazine or get work with a national brand is:
Polishing your photos so they look commercial or editorially done for submission.
Print your images. Research modeling comp card printers. Usually you can get comp cards for under 150$ for 100 of them. Or if you can't find a printing places there are other options. Usually a photo printed at least 5x7 inches will do.
Researching magazines and the editorial staff and products, brands, you want to get in touch with.
Mail your photos with a lettting to the marketing, editorials, or photo department at the magazine.
If you haven't been in a magazine yet, or in an ad campaign, it isn't only because you don't have an agent, it is because you are not taking the steps to market yourself, which is really more simple than you might think.
In my book I talk about how the first tearsheets in a magazine I got, and modeling jobs I gained were from my own self will and promotion. So start promoting you and stop waiting around!