Hi,
It is quite natural that when a woman is
pregnant she put on some weight. This extra weight again reduce in this lactation phase ( breast feeding phhade) if you are doing exclusively breast feeding but at the same time this is a recovery phase for body and for that reason calorie and other requirements is increased in this time. So if you right now, want to calorie deficit diet, it may affects your milk production. You have mentioned that your weight is decreasing, means it's already started, just take some time. So right now you should not go for calorie deficit diet, rather you follow good balanced diet which will be good for you and your child.
Next Steps
If you want you can consult with me through this practo app for further details.
Health Tips
You can include milk, sago, garlic, almond, Fenugreek which are helping in milk production. You can include fresh fruits, vegetables, sprouts, salads these will help you to meet the needs of vitamins and also help in reduce some weight.