I've no doubt that what you are doing is helpful in some very small way. But it is not much, and its focus is narrow. If you have children then you are doing more to harm animal welfare than you've ever alleviated by being vegan.
I give money to people on the street but I recognize that while it makes me feel good about myself, it really does virtually nothing to help the problem. Indeed, I may unknowingly be contributing to bigger problems. On the other hand I am focusing on people instead of cows, so there's that.
Unless you are willing to exit this world, you are likely doing it more harm than good. Veganism is a nice gesture, but it is not much more than that.