Try convincing them to let you eat vegetarian to begin with since they might be more willing to work with that, at least that way you can cut out some things from your diet. If you get an allowance or maybe you can find a small job to earn money like a paper round. You could then buy your own tofu and meat substitutes and just cook them yourself to go with whatever meal your family is making or if you earn enough you could just make your own meals. You can't expect others to make vegan food for you or even buy it for you but you can try to take steps to provide these things for yourself. If you're really young and that's impossible or they won't even let you do that, try doing a lot of research online, gather articles and videos and make a presentation. Sit your family down and present your arguments and explain how important it is to you and you hope they will at least try to work with you to find compromises. Vegan diets aren't more expensive, especially if you cook in bulk. If worst comes to worst you'll have to wait until you're 18 but you will still have opportunities to make choices to lead a vegan lifestyle even if your parents force you to eat certain things. Any effort and changes you make counts.