Re: Low milk supply at 20 months
The best thing you can do for supply is to nurse frequently and to have a child who is nursing well. You could offer the breast more often, but at 20 months your child might or might not be interested in nursing more, and when he does nurse, he might not be that effective. A lot of older babies transition from nursing for both food and comfort to nursing primarily or even exclusively for comfort. They don't really care whether or not they get a lot of milk when nursing.
At this point, I think it's a great idea to introduce a bit more dairy to your child's diet, but keep in mind that "dairy" doesn't necessarily mean "cow's milk". You can offer drinkable milk but it's just as good to offer cheese and yogurt made from whole cow, goat, or sheep milk. Better in some cases, because not all kids like animal milk in a cup.
When it comes to the amounts you should be offering, I think the guidelines vary somewhat, depending on who you ask. but they seem to cluster around offering around 2 cups of milk or yogurt per day, or 1.5 oz of cheese. Not that much, relative to the size of the child. My guess is that offering liquid milk is not going to make much of a difference in your baby's weight gain.
Whether or not you go to great lengths to increase your own milk supply is really up to you. I personally wouldn't- it would be too much effort for too little gain, when I could just as easily offer animal milk in addition to my own. But that's me, and you're you! So do what feels right to you.
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