projectiles not correctly aiming in Unity2D

I have a ship game object which has a child turret prefab. I also have a projectile prefab which is fired when I click on the space. The turret rotates towards the mouse pointer and follows it. but when I click, while the projectile is being fired, it is slightly off in rotation, It misses the target by a recognizable margin.

 using UnityEngine;
 using System.Collections;
 
 public class TargettingController : MonoBehaviour
 {
     public Rigidbody2D laser;
     public float speed = 10f;
 
     void Update()
     {
         Vector3 upAxis = new Vector3(0, 0, -1);
         Vector3 mouseScreenPosition = Input.mousePosition;
         mouseScreenPosition.z = transform.position.z;
         Vector3 mouseWorldSpace = Camera.main.ScreenToWorldPoint(mouseScreenPosition);
         transform.LookAt(mouseWorldSpace, upAxis);
         transform.eulerAngles = new Vector3(0, 0, -transform.eulerAngles.z - 90);
 
         if (Input.GetMouseButtonDown(0))
         {
             FireLaser();
         }
     }
     void FireLaser()
     {
         Rigidbody2D laserClone = (Rigidbody2D)Instantiate(laser, transform.position, transform.rotation);
         laserClone.AddForce(transform.right * speed * Time.deltaTime * 100);
     }
 }

I suspect it has something to do with the parent transform. I am just a noob in this and have got just three days of experience. Please guide me through this.