A Minor Detail-or maybe not so minor

So tonight I was putting S to bed and I forgot I needed to change her sheets. I changed the sheets but not the pillowcase, because I had just changed it a couple of days ago. Her diaper leaked through, so that's why her sheets needed to be changed after only a day or 2. Normally, her pillow just gets tossed out of the bed, mainly for entertainment, so who thought it matteered anyway? The past couple of weeks, I noticed she neatly arranges her pillow on the bed. I thought this was a little strange, but she changes her routines all of the time. Back to tonight-I have only 2 different pillowcases that I use for her bed, one is solid pink(the one that was on the pillow), the other has a dog pattern on it. After I put her in bed, she was asking for the doggie pillow. I wouldn't have thought in a million years that she noticed the pillowcase. For the last year, she hasn't even used a pillow. This brings something horrible to mind. I had read a story long ago about a girl who had attachment problems. She was older, and one day she burst into tears and told her mother that she was sad that she gave away her baby bouncer. I am a saver of all kinds of things, particularly sentimental things. I have gotten S so many toys, most of them thrift store finds. As I did with my other kids, I always took cues from them about their abilities and interests, and got them appropriate toys, games, etc. So with S at such a disadvantage, I have gotten her more than most kids to help her catch up and develop. This leads me to the dilemma, what to get rid of? If she noticed the pillowcase, is she wondering where some of her old toys have gone? With a child who has had their life disrupted as she has, does she worry about what will stay and what will go? I'm talking about toys, people, her house? I just don't know the answer to that. I try to keep a toy that I'm going to get rid of out of sight for a while. That way if she should ask for it, I have hung onto it. How long before it's safe to get rid of? I wish I knew. Tonight I've discovered that she notices things I don't realize, so I need to re-think our daily life.