why wont my ship fire alternating guns?

Hello, thanks for taking the time to read this.

I am very new, and found some useful tutorials online but I have hit a wall in trying to change a few things from the tutorial. I got the ship to fire a shotprefab. I was excited but I designed a ship with two barrels on the end and I have tried to find ways to get them to fire alternatively, with no luck. here is my player controller script. with movement and what I think is a firing script. I tried parenting two empty game objects to the barrels and called them shotspawn and shotspawnB to see if I could change the firing point of my shotprefab. please help me get alternating gun fire?

public class PlayerController : MonoBehaviour {

     /// 1 - The speed of the ship
     
     public Vector2 speed = new Vector2(50, 50);
     
     // 2 - Store the movement
     private Vector2 movement;
     public GameObject shotprefab;
     public Transform Shotspawn;
     public Transform ShotspawnB;
     public float fireRate;
 
     private float nextFire;
     
     void Update()
     {
             // 3 - Retrieve axis information
             float inputX = Input.GetAxis ("Horizontal");
             float inputY = Input.GetAxis ("Vertical");
         
             // 4 - Movement per direction
             movement = new Vector2 (
             speed.x * inputX,
             speed.y * inputY);
             
             // 5 - Shooting
     }
         bool m_alternate = false;
         void FiringShots ()
     {
             if (Input.GetButton ("Fire1") && Time.time > nextFire) 
         {              
                 nextFire = Time.time + fireRate;
                 m_alternate = ! m_alternate;
                 if (m_alternate)
             {
                     Instantiate (shotprefab, Shotspawn.position, Shotspawn.rotation);
             }     else 
             {
                     Instantiate (shotprefab, ShotspawnB.position, ShotspawnB.rotation);
             }
         }
     }
 void FixedUpdate()
     {
         // 5 - Move the game object
         rigidbody2D.velocity = movement;
     }

}