Randomly Spawn Outside The Camera Field of View

I've been at this for a while now and can't seem to find a solution to my problem. I am trying to get the enemy to randomly spawn outside of the camera field of view. The problem I am having is that when ever I play the game, the enemy's always spawn in the corner of the screen. (I'm just using blocks because of testing)

Here is my scripts:

 public GameObject[] enemy;
 public int amount;
 private Vector3 spawnPoint;

 private float camMin;
 private float camMax;

 void Start()
 {
     camMin = Camera.main.orthographicSize;
     camMax = Camera.main.orthographicSize + 2;
 }

 void Update ()
 {
     enemy = GameObject.FindGameObjectsWithTag ("Enemy");
     amount = enemy.Length;

     if (amount != 10) 
     {
         InvokeRepeating ("spawnEnemy", 1f, 2f);
     }
 }

 void spawnEnemy()
 {
     spawnPoint.x = Random.Range (camMin,camMax);
     spawnPoint.y = Random.Range (camMin,camMax);
     spawnPoint.z = 0;

     Instantiate (enemy [UnityEngine.Random.Range (0, enemy.Length - 1)],spawnPoint, Quaternion.identity);
     CancelInvoke ();
 }

Thanks for the help!