It’s easy to explain how Leia remembers Padme, without any outside material. It’s because she has the Force. Plain and simple.
And yet leia said that she died when she was very young and NOT that she died when she was born ( which is how anyone would have talked if their parent had died in childbirth) . And that is because Leia’s mother WAS still alive during the first few years of her life when Jedi was written. Silly excuses cannot hide the fact that George forgot his own films and screwed up when doing the prequels.
Very young, newborn, whatever. Same thing in this case.
If Leia’s mother died giving birth, she wouldn’t tell Luke, a close friend in an intimate conversation, that she died when she was very young, she’d tell him she died giving birth and wouldn’t have memories of her at all.
Keep in mind that Leia doesn’t have any concrete memories of her mother, just the images and feelings she described.