I can imagine how difficult it can be to live with so many things around you and to live in a place where you “don't have the authority” to change those things. As you say: it makes a lot of visual noise. I understand your mother's position, but I think if you talk to her and suggest putting those things in a suitcase, in boxes, arranging them under the bed, making space, maybe, just maybe, she will agree. Good luck with that, friend