[Isabela]

Correct me if I am wrong but don't you need the breast tissue such as milk ducts -glandular lobules to stimulate lactation. Cis women can induce lactation by breast pumping and hrt forms breast tissue ducts 

If you don't have lobules (mammary gland) you cannot lactate, it's easy to understand
Some men do have pretty big breasts which is only fat tissue, don't confuse this with mammary glands
I do had some lactation when I was around 15yo with very few/small mammary glands, now I have much more and bigger mammary glands and cannot induce lactation, even with everyday breast pumping