How long should a chapter be?

Hi everyone, I have recently wrote chapter 7 to my book (Nydiria) but I'm unsure whether it's to short or not. Please help.

Chapter 7

The aircraft takes us higher into the sky until we can no longer see the deep black smoke that now fills the village of Oakland. What about the people that were left down there, did they escape as well? I turn to Astra as she sits next me clutching onto my hand. She hadn’t said two words since she has been on the aircraft.

“Huh, watch it that hurts!” cries Alex

A nurse injects some sort of medication into his leg to try and ease the pain before they take him away into a separate room. My mind starts to wonder about the red haired woman I saw back at the village. Who was she and did she start the fires. Astra moves closer to me and rests her head onto my shoulder.

“You should try and get some sleep Alaska. It’s going to be a long journey.” says Astra.

I close my eyes and feel myself slipping away but then I keep seeing that woman and those creatures. It’s like she is somehow imprinted onto my brain. Minutes go by and I’m still struggling to get some shuteye. Astra is long gone as she lays there sound asleep, hopefully dreaming of something better than this. I turn to my rucksack and imagine playing the flute. I’ll be home in the safety of my cosy cottage, away from all this. It’s a nice feeling to have that flute when I’m in trouble but what about the people who can’t escape all this madness. How do they cope with it all? Do they just suffer and try to carry on with their lives. I have to help them... no I need to help them, somehow. I slowly lift Astra’s head and place it onto my seat. I leave the room without making a sound. I walk past a room and see Alex lying on a table.

“Alex?” I say while opening the door.

He turns to me and smiles. I take a seat next to him. I notice that his leg has been bandaged from where the stone had fallen on him.

“It feels much better now, whatever they did to it.” says Alex.

“Where do you think their taking us?” I ask.

Alex slowly lifts up his hand and points to a picture on one of the walls. It’s an image of what looks like a giant dome covered in thousands of red lights. I have never seen anything like this before.

“What is this place?” I ask in amazement.

“It’s a training academy and is one of the best in Nydiria. It’s based on a floating island called Podium that can only be accessed by the air.” Explains Alex.

I stare at him for a while waiting for him to tell me that he’s joking but he doesn’t seem to be laughing about it.

“Why would we need to go to a training academy?” I ask forcefully.

Suddenly I hear the sound of the aircraft becoming dull and quiet as we feel it touch the ground. I run to the window and see streams of water flowing towards the edge of the island alongside trim cut grass that moves elegantly with the wind.

“We’re here!” says Astra with excitement as she bursts through the doors.

I help Alex to his feet as we follow Astra off the aircraft. Once we are outside, the aircraft lifts of the ground and flies away from the island. The dome looks so much bigger in reality and I start to become nervous. A figure of a muscular man emerges from the dome and begins to walk towards us in a stride. He’s wearing some sort of red gown with gold silk sewed through it.

“Welcome to Podium. You must be the three the voice of life was telling me about. My names Zest and I’m your couch for the week.” says Zest.

“Wait so he’s okay, the voice of life?” I ask

Zest smiles and tells us to follow him into the academy. The doors open and the view takes my breath away. The inside looks so much larger than the outside and there are so many different floors and stairs. He takes Astra and Alex to their rooms before I get to see mine. Along the way to my room I take advantage now that I have Zest to myself and ask him as many questions as I can.

I take a deep breath before I ask anything.

“What am I being trained for?” I ask

“All will be explained in due course but for now you should just concentrate on defending yourself.” Says Zest

I look at the ground in confusion as we finally reach my room.

“This is where you will be based for the week” explains Zest.

I open the door and take a look around at my new room. There is soft cream carpet on the floor and a double bed with a flat screen TV hooked on a wall. The bathroom is all tiled and done up with a walk in shower. This place is like heaven compared to my life outside of Nydiria.

“There is going to be a welcoming feast tonight in the main hall so be ready at seven. There are clean clothes in the closet for you.” says Zest as he walks out of my room closing the door behind him.

I take a quick shower and slip into something comfortable and tie my hair back. I wait on the bed until seven o’clock comes and I make my way down to the main hall. As I take my first few steps into the hall I see a large table filled with dishes upon dishes of different foods. My mouth starts to fill with saliva just staring at it. I see Alex and Astra waving me over. Astra is wearing a beautiful baby blue dress that brings out the deep blue in her eyes where as Alex is wearing a suit that makes him looks handsome and smart.

“This looks amazing. I can’t wait to tuck in!” says Alex with excitement as he picks up his knife and fork.

Astra snatches the fork of him and slaps his hand.

“Have some respect and wait until we are told to eat!” snaps Astra

I have a giggle to myself as Astra and Alex argue with one another. The seats begin to fill as people arrive. Once everyone is seated there is only two empty seats remaining. Zest emerges from the back exit of the hall and says a speech to everyone before taking his seat.

“I’d like to thank everyone who has turned up to our feast tonight to welcome our new guests and we hope that you enjoy your time here with us. Let today be the calm before the storm as tomorrow you will begin training. Now without further ado tuck in!” says Zest.

The sound of cutlery fills the room along with laughter and cheers. This is truly a warm welcome and nice of them to do this for us. However I keep getting an image of the red haired woman in my head that won’t seem to go away. Will I ever see her again and is she the one I’m training for? I decide to try and forget about her at least for tonight and so I begin to join everyone in the commotion. My eye suddenly catches a late comer to the feast as she hurries to the dinner table. At first her face resembles someone’s I have seen before but a name doesn’t come to mind. She takes a seat next to Zest at the top of the table and apologises for being late. Her eyes look across the table and meets mine, but then she quickly looks away in shock. Suddenly I realise who this skinny blonde haired girl was.... Kaila Beeton, what is she doing here?