Character controller is shaky/jittery

Hey Guys, Im using the code below to make the character move. It automatically jumps when it lands on platforms but it shakes/jitters specially when the player is going down and i cant work out why.. The character is a cube and doesnt have any extra colliders besides character controller.

 void Start ()
     {
         control = GetComponent<CharacterController>();
     
     }
     
     // Update is called once per frame
     void Update ()
     {    
         distanceTraveled = transform.localPosition.x;
         score +=  Time.deltaTime  * 20;
         move = new Vector3 (Input.GetAxis("Horizontal"),0f,0f);
         move *= playerSpeed;
 
         
         if(Input.GetKey(KeyCode.LeftArrow))
         {
 
             transform.forward = new Vector3(0f, 0f, -1f);
         }
         
         if(Input.GetKey(KeyCode.RightArrow))
         {
 
             transform.forward = new Vector3(0f, 0f, 1f);
         }
         
         if (!control.isGrounded)
         {
             gravity  += Physics.gravity * fallSpeed * Time.deltaTime;
         }
         else
         {
             gravity = Vector3.zero;
             gravity.y = jumpSpeed;
         }
         
         move += gravity;
         
         control.Move(move * Time.deltaTime);
 
     
     }