2D Camera for OpenTK with zoom, scale, translation and rotation

Camera.cs

    public class Camera
    {
        public Vector3 Position;
        public Vector3 Rotation;
        public Vector3 Scale = Vector3.One/3;

        public float Size = 1;

        public static Camera Main = new Camera();

        public void Update(float deltaTime)
        {
            if (Input.GetKey(OpenTK.Input.Key.W))
            {
                Position -= new Vector3(0, 1, 0)*deltaTime;
            }
            if (Input.GetKey(OpenTK.Input.Key.S))
            {
                Position += new Vector3(0, 1, 0)*deltaTime;
            }
            if (Input.GetKey(OpenTK.Input.Key.A))
            {
                Position -= new Vector3(1, 0, 0)*deltaTime;
            }
            if (Input.GetKey(OpenTK.Input.Key.D))
            {
                Position += new Vector3(1, 0, 0)*deltaTime;
            }
            if (Input.GetMouseButton(OpenTK.Input.MouseButton.Left))
            {
                Rotation.Z += Input.MouseYDelta*deltaTime;
            }

            Size += -Input.MouseScrollDelta * deltaTime;
            Size = Size.Clamp(0, 1000);
        }


        public void Render(int width, int height)
        {
            GL.MatrixMode(MatrixMode.Projection);
            GL.LoadIdentity();



            Matrix4 proj =
                       Matrix4.CreateTranslation(new Vector3(-Position.X*width, -Position.Y*height,-Position.Z))*
                        Matrix4.CreateScale(Scale.X, -Scale.Y, Scale.Z) * Matrix4.CreateRotationZ(Rotation.Z)*
                      Matrix4.CreateOrthographic(width*Size, height*Size, 0, 1000) 
                   ;
            GL.LoadMatrix(ref proj);

            GL.MatrixMode(MatrixMode.Modelview);
        }

    }