If you are breast-feeding, you don't have to worry about the influence of vegetarianism on milk. Aren't all cows vegetarian?
It is very unscientific to say that "you can't eat vegetarian food in confinement". I don't know where it came from Maybe it's because of the poor conditions in difficult times. In order to take care of the confinement, I got more eggs, meat and the like to continue my habit. Things are different now. Most people are not malnourished, but overnourished. Eat more vegetarian food, just for balance.
It is suggested to eat more whole grains, such as rice, millet, brown rice, purple rice, black rice, barley, wheat kernels, oats, buckwheat and all kinds of beans to make porridge and rice paste with balanced nutrition, comprehensive vitamins and trace elements, which is beneficial to mothers and nursing children.