Could someone please help with making an enemy sprite flip when going the other way?

Hi
I am in the process of making a 2d platformer and have got a simple enemy sprite who I have managed to get moving back and forth, but I am really having issues with getting the sprite to flip when going the other direction.
I have tried various different ways but I have a feeling that the movement script I am using makes it difficult.
I have spent the last 4 hours trying to get this to work and have become very frustrated!
This is the script I am using to move him and I have tried adding a flip function but the sprite goes crazy when he reaches the point where he should flip.
using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class GroundEnemyMove : MonoBehaviour
{

    private Vector3 posA;
    private Vector3 posB;
    private Vector3 nextpos;
    public bool facingLeft;
    [SerializeField]
    public float speed;
    [SerializeField]
    private Transform Enemy;
    [SerializeField]
    private Transform transformB;
    // Use this for initialization
    void Start()
    {
        posA = Enemy.localPosition;
        posB = transformB.localPosition;
        nextpos = posB;
    }

    // Update is called once per frame
    void Update()
    {
        Move();
    }

    void Flip()
    {
        facingLeft = !facingLeft;
        Vector3 theScale = transform.localScale;
        theScale.x *= -1;
        transform.localScale = theScale;
    }

    private void Move()
    {
        Enemy.localPosition = Vector3.MoveTowards(Enemy.localPosition, nextpos, speed * Time.deltaTime);
        if (Vector3.Distance(Enemy.localPosition, nextpos) <= 0.1)
        {
            ChangeDestination();
        }


        }

    private void ChangeDestination()
    {
        nextpos = nextpos != posA ? posA : posB;
        transform.position = nextpos;
        Flip();
    }


}

Have you checked here? Unity - Scripting API: SpriteRenderer.flipX

I would try something along the lines of, If the enemy has a velocity below 0(he would move left), then flip the image