Can't sleep

I've been staring at a picture of Santorini that I have on my wall for the past hour because I can't sleep. The stone white walls against the deep, clear blue water. If I close my eyes and try hard enough, I can still feel myself riding our donkey's up the steps to reach Oia. The warm sun against my back and the smell of clean air and water. I can remember walking through the little alley ways filled with boutiques and cafes. I remember sitting at Cafe Kastro, and wishing that that day would never end. That I wouldn't have to go home at some point. I felt so safe and so serene, like nothing else was relevant. It's times like these, when I have a quiet moment to think, whether it's right before bed or right when I wake up and I can't quite distinguish dream from reality yet, that I miss Greece the most. It's not even the island life or the adventures or the traveling. It's the little things. I miss walking into my apartment and seeing the warm afternoon sun shining in from the balcony onto my bed or just chatting with my roommates as we lay in our beds. I even miss sitting on my balcony desperately trying to steal internet while the elementary school kids from across to street try to play juvenile tricks on me. I can still remember all these things vividly, from walking into Arcadia and seeing Petros, Maria, Jenny, Joanna, and Jan to everyone's apartment and the distinct smell each place has. I feel like these memories are more vivid now than they were when I first came back. I feel a pang of sadness and a knot tightens in my stomach every time I remember. Maybe it's because I've had time to digest and reflect. But I'm afraid that one day I'll forget. I feel like I'm desperately trying to grasp onto something that I know is slipping away, no matter how hard I try. Greek words that used to roll right off my tongue are now lost somewhere in my unconsciousness.
I feel like there's a void that's been in me since I left Greece and I still don't quite know how to completely fill it.