need help fixing third person character controller

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 using UnityEngine.UI;
 
 public class characterMovement : MonoBehaviour
 {
     //variables and functions
     public float moveSpeed;
     bool attackcooldown = true;
     public float health = 100f;
     float oldhealth = 100f;
     public bool dead = false;
     bool canheal = true;
     Vector3 moveDirection;
     void Start()
     { 
         moveSpeed = 1f;
         health = 100;
         dead = false;
     }
     void FixedUpdate()
     {
         //movement
         if (dead == false)
         {
             if (new Vector3(Input.GetAxisRaw("Vertical"), 0, Input.GetAxisRaw("Horizontal")).magnitude != 0) 
             {
                 gameObject.GetComponent<Rigidbody>().AddForce(moveDirection * moveSpeed, ForceMode.Acceleration) ;
             }
         }
 
     }
     //update loop
     void Update()
     {
         //moveDirection updating
         moveDirection = (GameObject.Find("Camera Holder").transform.GetChild(0).transform.forward * Input.GetAxisRaw("Vertical") + GameObject.Find("Camera Holder").transform.GetChild(0).transform.right * Input.GetAxisRaw("Horizontal")).normalized;
         moveDirection = new Vector3(moveDirection.x, 0, moveDirection.z);
         //death
         if (health < 1)
         {
             if (dead == false)
             {
                 dead = true;
             }
         }
         //attacking
         //if (Input.GetKeyDown(KeyCode.Mouse0) && attackcooldown && dead == false)
         //{
             //StartCoroutine(waiter());
             //IEnumerator waiter()
             //{
                 //GameObject.Find("Main Camera").transform.GetChild(0).transform.GetChild(0).GetComponent<Animation>().Play();
                 //attackcooldown = false;
                // yield return new WaitForSeconds(0.1f);
                 //GameObject.Find("Main Camera").transform.GetChild(0).transform.GetChild(0).transform.GetChild(0).GetComponent<TrailRenderer>().emitting = true;
                 //yield return new WaitForSeconds(0.3f);
                 //RaycastHit hitinfo;
                 //if (Physics.Raycast(GameObject.Find("Main Camera").transform.position, GameObject.Find("Main Camera").transform.forward, out hitinfo, 2f))
                 //{
                     //GameObject clone = Instantiate(GameObject.Find("hiteffectsone"), hitinfo.point, Quaternion.Euler(0, 0, 0));
                     //GameObject clonetwo = Instantiate(GameObject.Find("hiteffectstwo"), hitinfo.point, Quaternion.Euler(0, 0, 0));
                     //clone.GetComponent<ParticleSystemRenderer>().material = hitinfo.transform.gameObject.GetComponent<Renderer>().material;
                     //clone.GetComponent<ParticleSystem>().Emit(15);
                     //clonetwo.GetComponent<ParticleSystem>().Emit(10);
                     //Destroy(clone, 10);
                     //Destroy(clonetwo, 10);
                 //}
                 //yield return new WaitForSeconds(0.1f);
                 //GameObject.Find("Main Camera").transform.GetChild(0).transform.GetChild(0).transform.GetChild(0).GetComponent<TrailRenderer>().emitting = false;
                 //yield return new WaitForSeconds(GameObject.Find("Main Camera").transform.GetChild(0).transform.GetChild(0).GetComponent<Animation>().clip.length - 0.5f);
                // attackcooldown = true;
            // }
         //}
         if (Input.GetKeyDown(KeyCode.LeftShift) && dead == false)
         {
             moveSpeed = 45f;
         }
         if (Input.GetKeyUp(KeyCode.LeftShift) && dead == false)
         {
             moveSpeed = 30f;
         }
         if (new Vector3(Input.GetAxisRaw("Vertical"), 0, Input.GetAxisRaw("Horizontal")).magnitude != 0)
         {
             transform.GetChild(0).transform.LookAt(transform.GetChild(0).transform.position + moveDirection);
         }
             
         if (canheal == true && dead == false)
         {
             StartCoroutine(healing());
             IEnumerator healing()
             {
                 canheal = false;
                 if (health < 100)
                 {
                     health = health + 1;
                 }
                 yield return new WaitForSeconds(0.5f);
                 canheal = true;
             }
         }
     }
 }

i need help with the actual rigidbody movement of this script, note: PLEASE IGNORE ALL THE STUFF THAT IS NOT RELATED TO RIGIDBODY MOVEMENT, THAT IS ALL STUFF PLANNED FOR WHEN I GET THIS DONE

my issue here is that the rigidbody constantly moves left relative to the camera, various things ive tried are: -changing ways i calculate the movedirection variable -switching from velocity to addforce -messing around with physics material stats -changing my hierarchy from rotating the entire capsule to rotating just a mesh - and lastly, changing movespeed values and cutting out a camera bob system out of fear it would tamper with the movedirection variable (its all relative to the camera so if the camera is moving i figured it would get screwed up)

few things to note: the rotation of the mesh works fine, it turns left relative to the camera when i hit a, right when i hit d, forward when i hit w, and so on, so i believe its an issue with physics and not the movedirection variable

feel free to ask for any additional information, dont want to clutter my post too much though right off the bat