. Mums with disabilities/medical conditions, babies with disabilities/medical conditions, babies who are born prematurely, mums separated from their babies and mums on medication that means they can't breastfeed.
Dd was prem & in hospital so we were separated. I still managed to breastfeed.
I think the bit most people struggle with isn't milk supply, or the stuff above.
Its milk storage capacity and imho its the bit not talked about enough. For some people, they absolutely can produce "enough milk", but their breast storage capacity is small, so their baby is going to want to feed very regularly. This is often confused for poor milk supply when in fact its more that there simply isn't as much in one go.
If you are in this camp, it might be really exhausting trying to feed almost hourly in that first 6 months where breastmilk is the babies only source of food. Its probably not going to work without you co-sleeping and having a lot of family support. In the past or in a traditional close knit community where a woman's mum/aunties are on hand to help with cooking & caring for other DC might probably be ok. In a modern set up, less so.
If you are really well informed about this and determined, you might soldier through knowing its likely to get easier when baby starts solids and breastmilk gradually shifts to being more about immunity & comfort than the sole source of nutrition.
Then the other thing I wish lactation consultants were more honest about. Your breastmilk supply regulates in the first 3 months or so. After this, for many women its well nigh impossible to materially increase from the level it regulates to. If it drops a bit at some point because baby is ill and feeds less, you can get it back up to that regulated level, but its much harder without medication to recover to a much higher level than you ever had. So if you got off to a rough start and maybe had a tiny prem baby, or mixed fed or did bottles at night, and your supply settles at a lower level, after 3 or 4 months its incredibly hard to significantly increase it, even if you power pump, feed the baby loads.
Also often the way you "increase" the supply is feeding the baby the same volume but more often, whereas what most people want is for the baby to take a bigger feed and then last a couple of hours.