To make the transition to be vegetarian, you need to make an action plan on how to substitute with other foods in particular foods with high protein. Society stating that to be vegetarian is unhealthy have no basis of research, knowledge and practicality behind them. There are a variety of meals and food items available today that contain excellent nutrients and protein. This is in addition to your vitamins.
One great example that I would like to suggest, is to replace that daily chocolate bar/biscuit with a delicious protein bar that on average contains 22g of protein and less teaspoons of sugar. Not only is this a healthier option for you, they taste great and keep you feeling more sustained, far longer than a chocolate bar.