My cloth constriants dont work

im trying to create a simple cloth simulation such that it responds to forces such as gravity and inertia, im using verlet integration for this, after I got that working it was time to add the constraints but I cant get them to work, heres the code and a screenshot, details about the code are below the screenshot

using UnityEngine;
using System.Collections;
using System.Collections.Generic;

public class CustomCloth : MonoBehaviour
    [SerializeField] private Vector3 constForces;
    [SerializeField] private List<int> frozenVerts;

    [SerializeField] private GameObject checkCube;
    [SerializeField] private int Index;

    private List<int> usedVerts = new List<int>();
    private float reqDist;
    private Vector3[] vertices, oldPos, curPos;
    private Vector3 objectPrevPos;
    private Mesh mesh;

    void Start()
        objectPrevPos = transform.position;
        mesh = GetComponent<MeshFilter>().mesh;
        vertices = mesh.vertices;

        curPos = vertices;
        oldPos = vertices;

        reqDist = Mathf.Abs((vertices[0] - vertices[1]).magnitude);

    private void FixedUpdate()
        mesh.vertices = vertices;
        usedVerts = new List<int>();

        checkCube.transform.localPosition = vertices[Index];

    private void Simulate()
        for(int i = 0; i<vertices.Length; i++)
            if (!frozenVerts.Contains(i))
                Vector3 thisCurPos = curPos[i] + transform.position;
                Vector3 thisOldPos = oldPos[i] + objectPrevPos;
                Vector3 newPos = thisCurPos + (thisCurPos - thisOldPos);
                newPos += constForces * Time.deltaTime;

                oldPos[i] = curPos[i];
                curPos[i] = newPos-transform.position;
                vertices[i] = curPos[i];

            int secondIndex = FindNearestVertexIndex(vertices[i]);
            Vector3 secondVert = vertices[secondIndex];
            float dist = Vector3.Distance(vertices[i], secondVert);
            float error = dist - reqDist;
            Vector3 changeDir = (vertices[i] - secondVert).normalized;
            Vector3 changeAmount = changeDir * error;

            vertices[i] -= changeAmount * 0.5f;
            secondVert += changeAmount * 0.5f;
            vertices[secondIndex] = secondVert;
        objectPrevPos = transform.position;

    int FindNearestVertexIndex(Vector3 vert)
        int nearestVertexIndex = -1;
        float nearestDistance = float.MaxValue;

        for (int i = 0; i < vertices.Length; i++)
            float distance = Vector3.Distance(vertices[i], vert);
            if (distance < nearestDistance && !usedVerts.Contains(i))
                nearestDistance = distance;
                nearestVertexIndex = i;

        return nearestVertexIndex;


Currently, I have disabled gravity
These are the results I got when I manually moved the cloth a little down
The vertices on the far left are frozen (added to a certain list of vertex indexes in my cloth script, these vertices dont respond to any forces or movements)

About the script:
The gameobject checkCube and int Index are used for testing, dont worry about them
The vector 3 constForces is used to add forces such as gravity, it is 0,0,0 in the screenshot
The method 'FindNearestVertexIndex returns the index of the nearest unused vertex, to use as a reference for calculating distance