Spawning different enemies for different levels

Hello everyone. I am making a 2D shooter and I want to introduce new enemies after certain levels are reached. I created a GameObject[] called enemies. I added 2 enemy prefabs to the Array. It's working except that when level 6 is reached, I want to ONLY start spawning enemy[1] not enemy[0] but it keeps spawning both. Can anyone see what I'm doing wrong?

 function LevelEnd(){
 
     EnemySpeed += -.1;
     
     if(level <=5){
         while(totalEnemies < level){
         posX = Random.Range(-4.213592,4.336067);
     
         yield WaitForSeconds(3);
         Instantiate(enemies[0], Vector3(posX, 0.1, 3.545458),transform.rotation);
         }
     }
     if(level >= 6 && level < 10){
         while(totalEnemies < level){
         posX = Random.Range(-4.213592,4.336067);
     
         yield WaitForSeconds(3);
         Instantiate(enemies[1], Vector3(posX, 0.1, 3.545458),transform.rotation);
         }
     }
     if(level >= 10 && level < 15){
         while(totalEnemies < level){
         posX = Random.Range(-4.213592,4.336067);
     
         yield WaitForSeconds(3);
         Instantiate(enemies[1], Vector3(posX, 0.1, 3.545458),transform.rotation);
         }
     }
 }

EDIT GameController.js function Update () { if(!playerspawning){ timer += Time.deltaTime; } //when timer reaches 2 seconds, call Spawn function if(timer >= 2){ Spawn(); }

         if(level == 0 ||cash == level * 200){
                 level++;
                 LevelEnd();
             }
         }
     
     function LevelEnd(){
         //I don't know about the rest of your code, but you have to do 
         //something like this:
         totalEnemies = 0;
     
         EnemyMovement.EnemySpeed += -.1;
     
         if(level <=5){
            while(totalEnemies < level){
            posX = Random.Range(-4.213592,4.336067);
     
            yield WaitForSeconds(3);
            Instantiate(enemies[0], Vector3(posX, 0.1, 3.545458),transform.rotation);
            // Update your totalEnemies variable
            totalEnemies++;
            }
         }
     
         if(level >= 6 && level < 10){
            while(totalEnemies < level){
            posX = Random.Range(-4.213592,4.336067);
     
            yield WaitForSeconds(3);
            Instantiate(enemies[1], Vector3(posX, 0.1, 3.545458),transform.rotation);
            // Update your totalEnemies variable
            totalEnemies++;
            }
         }
     
         if(level >= 10 && level < 15){
            while(totalEnemies < level){
            posX = Random.Range(-4.213592,4.336067);
     
            yield WaitForSeconds(3);
            Instantiate(enemies[1], Vector3(posX, 0.1, 3.545458),transform.rotation);
            // Update your totalEnemies variable
            totalEnemies++;
            }
         }
     }

EnemyMovement.js var enemySpeed:float; static var CoastguardSpeed:float;

 function Awake(){
     enemySpeed = EnemySpeed;
 }
 
 function Update () {
     transform.Translate(0,0,enemySpeed * Time.deltaTime);
     if(transform.position.z < -2.04){
         GameController.totalEnemies -= 1;
         Destroy(gameObject);
     }
 }