How to create a proper jumping and doublejumping system for 2.5D platformer on Unity?

Question

First jump image:

Second jump image:

using UnityEngine;

public class Player : MonoBehaviour
{
    [Header("Move Settings")]
    [SerializeField] float jumpSpeed = 5f;
    [SerializeField] float normalSpeed = .2f;
    [SerializeField] float slowSpeed = .01f;
    [SerializeField] float slowAnimationSpeed = .02f;


    [Header("CastBox Settings")]
    public Vector3 boxsize;
    public float maxDistance;
    public LayerMask layerMask;

    //Cached References
    private Rigidbody playerRigidBody;
    private Animator playerAnimator;

    //Properties
    private bool canDoubleJump = false;

    private Vector3 jumpInput;
    private float moveSpeed;

    private enum PlayerState { jumped, doubleJumped, onGround };
    PlayerState playerState;

    //animationstate
    [SerializeField] float PlayerYLimit = 2.85f;

    private void Awake()
    {
        playerRigidBody = GetComponent<Rigidbody>();
        playerAnimator = GetComponentInChildren<Animator>();
    }

    private void Start()
    {
        moveSpeed = normalSpeed;
        ChangePlayerState(PlayerState.onGround);
    }
    private void Update()
    {
        UpdateAnimationState();
        Move();
        GroundCheck();
    }

    private void UpdateAnimationState()
    {
        if (transform.position.y > PlayerYLimit)
        {
            playerAnimator.SetBool("Jump", true);

        }
        else if (transform.position.y < PlayerYLimit)
        {
            playerAnimator.SetBool("Jump", false);
            playerAnimator.SetBool("DoubleJump", false);
        }

    }

    private void Move()
    {
        if (Input.GetKey(KeyCode.LeftShift) && GroundCheck())
        {
            SlowSpeed();
        }
        else
        {
            NormalSpeed();
        }
        transform.position += Vector3.right * moveSpeed * Time.deltaTime;
    }

    private void ChangePlayerState(PlayerState newPlayerState)
    {
        playerState = newPlayerState;
        Debug.Log(playerState);
        if (playerState == PlayerState.jumped)
        {
            canDoubleJump = true;
        }
        else if (playerState == PlayerState.doubleJumped)
        {
            canDoubleJump = false;
        }
        else if (playerState == PlayerState.onGround)
        {
            canDoubleJump = false;
        }
    }

    private void OnJump()
    {
        if (playerState == PlayerState.onGround)
        {
            ChangePlayerState(PlayerState.jumped);
            Jump();
        }
        else if (playerState == PlayerState.jumped && canDoubleJump)
        {
            ChangePlayerState(PlayerState.doubleJumped);
            Jump();
            playerAnimator.SetBool("DoubleJump", true);

        }
    }

    private void Jump()
    {
        jumpInput = Vector3.up * jumpSpeed * Time.deltaTime;
        playerRigidBody.AddForce(jumpInput, ForceMode.Impulse);
    }

    private void SlowSpeed()
    {
        moveSpeed = slowSpeed;
        playerAnimator.speed = slowAnimationSpeed;
    }

    private void NormalSpeed()
    {
        moveSpeed = normalSpeed;
        playerAnimator.speed = 1;
    }

    bool GroundCheck()
    {
        var isGrounded = Physics.BoxCast(transform.position, boxsize,
            -transform.up, transform.rotation, maxDistance, layerMask);

        if (isGrounded)
        {
            ChangePlayerState(PlayerState.onGround);
            return true;
        }
        else
        {
            return false;
        }
    }

    private void OnDrawGizmos()
    {
        Gizmos.color = Color.red;
        Gizmos.DrawCube(transform.position - transform.up * maxDistance, boxsize);
    }
}

I am trying to make a 2.5D platformer endless runner on Unity. As you can see at the code i am trying to create a doublejump system. First Jump and Doublejump works correctly. But then it don't. The jumps after first jump are very short. I printed a massage after every Jump and looks like it doesn't register multiple times at first jump. I can't find a working solution to make this jump system work. If i have to change entire logic i am ok with that. But i still want to learn what i am doing wrong. I added two screenshots of my player with ground and without ground. That red thing behind player is boxcast.