Shooting bullets up (y axis)

Hello!

I would like to shoot bullets in my 2D Platformer up. I have managed to shoot left or right. I know it is a little bit stupid not to work with rigidbody2d but I have a very smooth character controller and for now I am a little bit lazy to write a new movement script,

So here is my blockshooting script:

 using UnityEngine;
 using System.Collections;
 
 public class BlockShooter : MonoBehaviour {
     public Transform bulletPosition;
     public AudioClip shootSound;
     public Sprite[] shoot;
     public float bulletSpeed = 16.0f;
     private bool shooting = false;
     private float counter = 1.0f;
     public GameObject enemyBullet;
     public GameObject enemyBulletUp;
     private SpriteRenderer rend;
     public bool y = false;
 
     // Use this for initialization
     void Start () {
         rend = GetComponent<SpriteRenderer>();
     
     }
     
     // Update is called once per frame
     void Update () {
         counter -= Time.deltaTime;
         if (counter < 0)
         {
             StartCoroutine(shootBullet());
             rend.sprite = shoot[1];
         }
         /*if(shooting){
                 rend.sprite = shoot[0];
                 
         }*/
     
     }
 
     public IEnumerator shootBullet () {
         shooting = true;
         counter = 1.0f;
         //we wait for a bit before the shot fires so that the player can see he's about to do it
         yield return new WaitForSeconds(0.5f);
         rend.sprite = shoot [0];
         //play the shot sound
         GetComponent<AudioSource>().PlayOneShot(shootSound);
         if (y == true) {
             GameObject bullet = Instantiate(enemyBulletUp, bulletPosition.position, Quaternion.Euler(0,0,90)) as GameObject;
             Debug.Log("Y is true");
             bullet.GetComponent<Rigidbody>().velocity = new Vector3(GetComponent<Rigidbody>().velocity.x, 20, GetComponent<Rigidbody>().velocity.z);
         }
         //spawn the bullet
         GameObject bullet1 = Instantiate(enemyBullet, bulletPosition.position, Quaternion.Euler(0,0,0)) as GameObject;
 
         //set velocity to the bullet
         if(bulletPosition.position.x < transform.position.x){
             bullet1.GetComponent<Rigidbody>().velocity = new Vector3(-bulletSpeed,0,0);
         }else{
             bullet1.GetComponent<Rigidbody>().velocity = new Vector3(bulletSpeed,0,0);
         }
         //then pause again before the enemy is ready to fire again.
         yield return new WaitForSeconds(0.5f);
         shooting = false;
     }
 }
 

I think I do something wrong in the if(y==true) section. I have two bulletprefabs because at the one is the x postion freezed and at the other the y position,

I hope someone can help me.

Greetings.