Who said that animals should be tortured? This is cruel and evil way to do it. Animals should be killed quickly, humanely, painlessly, and respectfully. And they should be treated well for their whole lives before this.
Because simply there are nutrients that your body requires which are only possible to get from animal sources.
Myelin is the substance that surrounds every nerve in your body and in your brain. This works exactly the same way as the plastic insulation surrounding a wire, and for the same purpose. Myelin is only coming from animal sources specifically animal fat. Vegetable oils do not contain the correct materials to create myelin. When the myelin is degraded over time of not being regenerated from not consuming the materials required to build it, eventually you will have serious nerve problems. As the insulation is gone, you will have the signal from one nerve being sent into the nerve next to it when they are supposed to be seperate. Or you will have a signal in a nerve that does not go where it needs to go, because it was shorted and lost in another location. This is just like having a whole bundle of different wires, and cutting off the insulation so they are all sparking and shorting to each other. Throw a bucket of water into your computer and see how well it will work after that. This causes twitching, shaking, and weakness in these people. These are symptoms that all long term vegans have. Coconut fat is the closest you can get from an animal source, and you should be consuming a lot of "virgin" unprocessed unrefined coconut oil. This will help somewhat, but it still will not be enough on its own and you still would be deficient. The best is to combine animal fat and coconut fat together.
You also are not consuming any Vitamin B. This vitamin is naturally found in meat and animal fat, and it is not found at all in any kind of plant or vegetable. The vegan argument is that certain types of bacterias are able to generate vitamin B, and these bacterias might be living in the dirt. So if you eat dirty vegetables without washing away the dirt, you might possibly be able to consume some of this bacteria. Ignoring all of the parasites and dangerous bacterias that you would get from eating dirt, even if you did eat a dirty bacteria that has Vitamin B, it would not be enough.
The Vitamin B supplement pills are not natural and are not the actual nutrient that you need, they are a synthetically created chemical that is a little similar looking but not good enough. The synthetic vitamin B pills will help enough if you also have enough real vitamin B in your body, but they will very quickly stop working and stop having any effect. Vitamin B is necessary to create ATP which is the energy that is used in each cell in every process in your body. So with no Vitamin B, it will become extremely difficult for you to be able to make any ATP. And you will be extremely weak and tired all of the time. This can possibly kill you when it gets bad enough.
You also will not be consuming any calcium. It is true that many dark colored leaves in things like kale contain some calcium, but this is in a molecule that your body is not able to digest and is not able to absorb. So even with this, you are not actually getting any calcium. Your bones will be weak and will eventually break very easily, especially when you get older.
You can start with consuming eggs and milk every day. There is not a moral argument about these foods because you are not killing any animals. Chickens lay eggs all the time. Eggs contain most of the nutrients that you need, and milk or cheese will give you the calcium. This still is not really everything that you will need, but it is a great help and there will be an enormous improvement compared to not eating any animal products.