I was the only vegetarian in my house growing up (though I was really a vegan since I'm dairy intolerant and never ate eggs), and my parents didn't buy anything special for me or cook for me. I ate the vegetable sides my mother served with the meat, and made pb&j, or pasta when she didn't make vegetables. I ate a lot of rice -- usually I'd make some rice in the microwave to go with the vegetables. As long as your parents buy vegetables (canned, fresh or frozen), fruits (canned, fresh, frozen, etc) and grains (rice, pasta, bread, etc), and most families do, you will have food to eat. You can also ask them to buy you lentils and beans in a can or dry, and cook them yourself. They are only a few dollars. You can get a bag of beans for $1 and it will last you all week. Maybe also ask for an allowance or do chores for an allowance to buy things?