Hi don't worry I understand its a difficult situation, Your wife should eat everything homemade. Ask her to include Jeera, ajwain, saunf, garlic, daliya, oats, nuts, dry fruits, milk and milk products in her diet regularly. If you are a non vegetarian then please add eggs, chicken, fish, dry fish, mutton soup (daily) in her diet. She has to drink 4 litres of fluids every day, Daliya can be cooked with water and milk, ask her to drink before breakfast. Apart from all these she needs to latch the baby to her breast often. Her breast needs stimulation from her baby, so the more the baby latches more the milk.

Tell her to consume garlic, fenugreek,broken rice gruel thrice daily,also consume shathavari lehyam,u can get in ayurvedic shop