make sure you get enough vitamin B12 in your diet by eating vitamin B12 rich foods
Vitamin B12 Recommended Dietary Allowance (RDA) for lactating women is 2.8mcg. This means you should eat 2.8 mcg of the vitamin every day.
Here are several good options for Vitamin B12 rich food fit to your diet habits. Eating of several of those daily, can help in reaching the daily recommendations.