unity2d, trajectory prediction shaking - unity3d

Question

I'm making a mobile game that uses trajectory to find out the next path from my player. When the player is silent the trajectory works very well, but when the player is moving the trajectory sometimes moves on its own even though it returns to its proper position later, but this is very disturbing.
Here's the script:
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.SceneManagement;
using UnityEngine.UI;
public class PlayerMovement : MonoBehaviour
{
public static PlayerMovement Instance;
Rigidbody2D rb;
Vector3 startPos;
Vector3 endPos;
[HideInInspector] public Vector3 initPos;
[HideInInspector] public Vector3 direction;
public static Vector3 anotherSpeed; // Only for trajectory
float speedMultiplier = 1.5f;
public GameObject trajectoryDot;
GameObject[] trajectoryDots;
public int numbersOfTrajectory;
float trajectoryDotsDistance = 0.001f;
public static float energy = 100f;
public Slider energyBar;
float slowDownFactor = 0.3f;
private void Start()
{
if (!Instance)
Instance = this;
rb = GetComponent<Rigidbody2D>();
trajectoryDots = new GameObject[numbersOfTrajectory];
}
void Update()
{
anotherSpeed = direction;
if (!Pause.isPaused)
{
// Get Start Position
if (Input.GetMouseButtonDown(0))
{
// Instansiate The Trajectory
for (int i = 0; i < numbersOfTrajectory; i++)
{
trajectoryDots[i] = Instantiate(trajectoryDot,gameObject.transform.position, gameObject.transform.rotation);
}
}
// Get Position When Dragging
if (Input.GetMouseButton(0))
{
EnableSlowMotion();
// Get Drag Position
endPos = Camera.main.ScreenToWorldPoint(Input.mousePosition) + new Vector3(0, 0, 10);
startPos = gameObject.transform.position;
// Get The Speed
direction = endPos - startPos;
direction = direction.normalized;
direction = Vector3.Lerp(transform.position, direction, 500 * Time.deltaTime);
direction = direction * 18;
// Update The Trajectory Position
for (int i = 0; i < numbersOfTrajectory; i++)
{
trajectoryDots[i].transform.position = calculatePosition(i * trajectoryDotsDistance);
}
}
// Get Position When Realeasing
if (Input.GetMouseButtonUp(0))
{
DisableSlowMotion();
// enable Gravity
rb.gravityScale = 1f;
// Move The Player
rb.velocity = new Vector2(direction.x * speedMultiplier, direction.y * speedMultiplier);
// Destroy The Trajectory When Player Release
for (int i = 0; i < numbersOfTrajectory; i++)
{
Destroy(trajectoryDots[i]);
}
}
}
CameraZoom();
ControlsChecker();
}
// Calculate The Trajectory Prediction
Vector2 calculatePosition(float elapsedTime)
{
return new Vector2(startPos.x, startPos.y) +
new Vector2(anotherSpeed.x * speedMultiplier, anotherSpeed.y * speedMultiplier) * elapsedTime +
0.5f * Physics2D.gravity * elapsedTime * elapsedTime;
}
// Check Controls Is pull or push
void ControlsChecker()
{
if (PlayerPrefs.GetInt("Controls") == 1)
{
direction = direction;
anotherSpeed = anotherSpeed;
}
else
{
direction = -direction;
anotherSpeed = -anotherSpeed;
}
}
void EnableSlowMotion()
{
Time.timeScale = slowDownFactor;
Time.fixedDeltaTime = 0.02f * Time.timeScale;
}
void DisableSlowMotion()
{
Time.timeScale = 1f;
Time.fixedDeltaTime = 0.02F;
}
}
void CameraZoom()
{
if (Input.GetMouseButton(0))
{
vcam.m_Lens.OrthographicSize += 0.1f;
if (vcam.m_Lens.OrthographicSize >= maxZoom)
{
vcam.m_Lens.OrthographicSize = maxZoom;
}
}
else if (Input.GetMouseButtonUp(0))
{
zoomIn = true;
}
if (zoomIn)
{
vcam.m_Lens.OrthographicSize -= 0.2f;
if (vcam.m_Lens.OrthographicSize <= minZoom)
{
vcam.m_Lens.OrthographicSize = minZoom;
zoomIn = false;
}
}
}
so I get the player's movement direction from the calculation based on the point where I touch and the point when I release touch (dragging). Did I make a mistake in the code that caused my trajectory to vibrate often? I really need help here, thanks in advance.