This post comes late , but you may have Insufficient glandular tissue (IGT). This is what i had. (yes i know low supply can be from a c-section, a bad latch, medication etc. but I wanted to share that this condition exists).
My grandmother had told me as a child that women in her family didn't produce milk, or produced very little so when mine didn't come in (very VERY little, like drips) i knew something was wrong and it wasn't that i wasn't pumping enough or my c-section. We started supplementing quickly but i kept trying to breastfeed.
I was lucky to hear of a breastfeeding doctor through our tongue tie doctor, one of like 20 in the country, that happened to be in my city. She helped me come to terms with the best i would have is a low supply and prescribed medication that actually helped me grow tissue. I successfully breastfed for 9 months- of course with supplement. I'm now expecting my second baby and am already prepping for a similar experience under her care.
Signs that you may have this condition are uneven breasts, Poly-cystic ovarian syndrome, underdeveloped breasts, and family history. These aren't the only ones (see google and a good doctor/lactation specialist). Basically, for some reason during puberty your tissue didn't developed the way it should have and you don't have developed milk glands capable of producing milk. I think if this was more talked about women with this condition would feel more comfortable and less attacked about their feeding plan.
Hope this helps someone.
