To get a modeling agency interested in you consider these 3 tips:
1. Get a Tearsheet, sometimes if you can show you can work, and have worked it helps to intrigue an agent. You might get a chance despite being considered too short normally.
2. Call the agency and ask what photographers they test with. Even if this means you have to fork out some money to test with the photographer, if you tell the photographer you are really interested in the agencues he works with maybe he will tell the agent about you.
3. Submit over and over. Just because you get a no, doesn't mean in a few weeks or a month you can't try again with new photos and keep up dating and improving your pictures.
4. Scope out their website. Look at what models they work with, and see what similar models they have to you, and try to get images in a similar style.