issue with moving GameObject consistently

So here is what i'm trying to do: MainPlayer will run upwards endlessly, when there is a swipe from left to right or right to left he will switch lanes. Here is the code for mainplayer:

  using UnityEngine;
 using System.Collections;
 
 public class CharTouchCont: MonoBehaviour
 {
     public float moveSpeed = 3f;
     public float swipeVelocity = 9f;
     public float timeThreshold = 0.35f;
     // swipe related variables
     private bool canSwipe;
     private Vector2 startPosition; 
     private Vector2 endPosition;
     void Start ()
     {
         canSwipe = true;
     }
     
     void Update ()
     {
         rigidbody2D.velocity = new Vector2 (0, moveSpeed);
         if (Input.touchCount == 1 && Input.GetTouch (0).phase == TouchPhase.Ended && canSwipe == true) // End of Touch
         {
             canSwipe = false; 
             endPosition = Input.GetTouch (0).position;
             if (startPosition.x < endPosition.x) // left to right swipe
             {
                 rigidbody2D.velocity = new Vector2 (swipeVelocity, rigidbody2D.velocity.y);
                 StartCoroutine ("delay");
             }
             else if (endPosition.x < startPosition.x) // right to left swipe
             { 
                 rigidbody2D.velocity = new Vector2 (-swipeVelocity, rigidbody2D.velocity.y);
                 StartCoroutine ("delay");
             }
         }
         if (Input.touchCount == 1 && Input.GetTouch (0).phase == TouchPhase.Began && canSwipe == true) // Start of Touch
             startPosition = Input.GetTouch (0).position;
         if (Input.GetKey (KeyCode.Escape))
             Application.Quit ();
 
     }
     IEnumerator delay ()
     {
         yield return new WaitForSeconds (timeThreshold);
         rigidbody2D.velocity = new Vector2 (0, rigidbody2D.velocity.y);
         canSwipe = true;
     }
 }

i'm trying to move him to left or right by increasing the velocity in x axis by 9 for 0.35 seconds and then setting it back to 0. so i will move left to right depending on swipe by 3.15 units ( 9 * 0.35) the issue is that after i run the game my character starts to stop at positions which are slightly to the left or right of where he should be or sometimes in between 2 lanes. How do i make it so that my GameObject will move 3.15 units to left or right consistently?