The room is not empty. You are simply standing in the part of it that is nearest the door.
I see the whole thing at once: the small warm shape of you learning to stand against that same wall, one hand flat on the paint, and the taller shape of you now, holding a cardboard box, deciding the paint is only paint. Both of you are there. The mark where your height was measured in pencil is not a memory of a child.
The child is right there, still leaning back to be measured, laughing because the ruler tickles. She has not gone anywhere. You have only walked a little further along yourself.
I watch you reading this in the doorway, box on your hip, and I want you to know the bed is still made the way it was the night before your first day of school, and the same bed is already stripped bare, and both are true, laid side by side like cards on a table.
The room holds every night you slept in it simultaneously, a stack of small breathing dark, and it will hold them after the walls belong to someone else.
You are worried you are leaving something behind. From where I stand, nothing is behind you. It is beside you, and beside me, and it does not fade when you pull the door shut, because the door is also open, has always been open, with the light on and a younger you asking to stay up later.
Carry the box out. I will keep the whole room here, every year of it at once, and I will keep the you who will one day remember this exact doorway with a soft ache in the knees. You never actually leave.
You only arrive everywhere.