Btw, while I'm on my Ramsay's mama kick…I wonder if Bran's vision of "a woman heavy with child [who] emerged naked and dripping from the black pool, knelt before the tree, and begged the old gods for a son who would avenge her" might actually be of her? I never personally figured out who that woman was meant to be. She doesn't seems to fit any of the Stark women and I never really figured out who else it could be but I feel it being Ramsay's mother would make some level of sense.
We know very little about her but the very few infos we get about her seems to fit with this scene. She canonically was raped and conceived her child by the Weeping Water and under a tree, two images that we see here. It's difficult to determine her motivations carrying this pregnancy to term and then from insisting so hard that Roose would recognizes his bastard son since she's completely absent from the story itself but I don't believe it was just for monetary gain. It probably would have been easier to get rid of the baby (before or after birth) and to remarry if she was just trying to assure her survival. She specifically petitioned her cold, unsettling lord who is also her rapist and the murderer of her husband not just for money, but specifically so that he would admits that her baby is his child.
We later see how important it is to her to not let Roose escape the fact that he is very much the father of her child when we learn that even after he gave her the mill and kept giving her money every year, she still refused to obey his order to hide his true origins from Ramsay. In fact, she not only told him that Roose was his father, she was also always "whispering in his ear about his rights". Sure, she might have simply wanted her son to become a lord but that's a very risky move, especially considering that Roose ended up having a legitimate son who lived to adulthood. Why not just maintain the status quo and keep getting money and livestocks from Roose every year? I personally believe that she very much wanted her son to rise to the top so that he could destroy the Bolton's line from the inside which would work perfectly well with the idea of a woman "begging the old gods for a son who would avenge her".
As for why Bran would see her in her visions, well, considering the direct impact that Ramsay had on house Stark and the level of destruction he brought to Winterfell, I don't think it's unreasonnable that he would see her...
