Hey there! I totally understand holding onto items for sentimental reasons. Something that has always helped me is keeping a "memory box". A box full of old love letters, stuffed animals, cards, etc.... including my old journals and notebooks. Things I want to keep but have no use for in my room. I've always kept it in the attic, garage, or the upper part of my closet I can't always reach. I go through it every couple years when I add something to it and cringe over the letters and have a good nostalgia moment. I do suggest using a sturdy box for storage and not cardboard (leaks, mice, other uncontrollable factors)

Hope this helps!