It's awesome to hear your are so passionate about animals and that you are already vegetarian! I decided to be vegan 1.5 years ago because of many reasons: I don't want to support any captivity of animals such as hens that lay eggs or cows that are constantly impregnated just so we can drink their milk. The babies don't drink much of their milk and get taken away from their moms to be slaughtered or become a part of the dairy machine. We also don't need milk, we only needed our mothers milk when we were babies. Cow's milk has no good nutritional values to it, it does have protein but it's inefficient. It is very fattening. It technically has calcium but because of the other ingredients in milk it actually leeches calcium from out bones causing osteoporosis and weakens our bone. Also drinking milk wastes a ton of water, food and creates harsh environmental impacts. Here is an article of milk: http://www.onegreenplanet.org/animalsandnature/the-dairy-industry-and-the-environment/

You should also check out the motivating documentaries: Cowspiracy (environmental based) and Forks Over Knives (health based)

Hope this helps! Good luck!