Good luck. My daughter tried the same thing to me and I blew up. No daughter of mines gonna be anything other than a carnivore. She has since changed her mind like I knew she would. She likes chicken too much.
Do a lot of research and fill out a few pages on why to be vegetarian and how to get what your missing in other foods. For example going dairy free your missing calcium, I can eat some almonds, broccoli, orange juice, etc. to get the missing calcium.
It is very difficult to be a pure vegetarian. When you pass around KFC, McDonald's, or if you see hot dogs, puddings, cakes, and when you attend some lunch or dinner party. All nonvegetarian foods are very tempting.
Do you really understand what a vegetarian diet entails? Have you discussed this with your doctor and have sound medical advice concerning vegetarianism? Do you know how you will make up the lack of proteins, fats, amino acids, and omega acids that meat provides?
If you don't have a sound plan, and you don't have solid advice from a doctor or dietician, you shouldn't just "become" vegetarian. That's a quick way to "become" anemic and sick.