Ask yourself why you can't model. After you tell someone you can't. Think about why?
Really it is only yourself. If you want to do something that is difficault, you have to accept it will be. You have know with a passion to over come the odds that you can.
If you want your modeling tearsheets and agents and work handed to you, then go back to bed and dream about being 5'10 or something. Besides having things handed to you makes life boring anyways, right. Chasing and trying is something that brings even other opportunities.
Being a petite model will be hard, every day you will face new goals and have to figure out how to chase them and get inside the door, get better photos, market yourself, and get ahead. But if you stay ambitious it will happen.
Don't tell me your can't model.