Game Object's Vector3 changing threw script without reason

0

I am trying to do a combine block script. However, i encountered 2 problems: the blocks / the combined mesh isn't showing up anymore, and when it was, all the blocks where at the same location (even tho the blocks are not showing up, i still ask to display the locations in the Debug Log and they are all the same). I check the locations at multiple places in the script, and i don't see why they changed.

  using System.Collections; 
 using System.Collections.Generic; 
 using System.Linq;
  using UnityEngine;
  public class ThisWorldGen : MonoBehaviour { 
 public GameObject meshy;
  public GameObject blockPrefab; 
 public GameObject grass;
  public GameObject dirt; 
 public GameObject rock;
  private string[] blockTag;
  private GameObject stockin;
 
 public int amp;
 public int freq;
 private Vector3 mypos;
 [SerializeField]
 private Material material;
 private Vector3 blockLocations;
 
 public List<MeshFilter> meshes = new List<MeshFilter>();
 
 void Start()
 {
     Generate();
 }
 
 void Generate()
 {
     amp = 2;//Random.Range(0,100);
     freq = 2;//Random.Range(30,100);
     mypos = this.transform.position;
     int cols = 100;
     int rows = 100;
     float startTime = Time.realtimeSinceStartup;    
     #region Create Mesh Data
     MeshFilter blockMeshes = Instantiate(blockPrefab, Vector3.zero, Quaternion.identity).GetComponent<MeshFilter>();
 
     for(int x = 0; x < cols;x++)
     {
         for(int z = 0; z < rows;z++)
         { 
             float y = Mathf.PerlinNoise ((mypos.x + x) / freq,(mypos.z + z)/freq) * amp;
             y = Mathf.Floor(y);
             int a1 = 0;
             for(float hy = y; hy > 0.0F; hy--)
             {           
 
                 blockMeshes.transform.position = new Vector3(mypos.x + 
  x,y,mypos.z +z);
                 Debug.Log(blockMeshes.gameObject.transform.position);//the 
  blocks positions are normal (all different)
                 meshes.Add(blockMeshes);  
                 Debug.Log(meshes[a1].gameObject.transform.position);//the 
  blocks positions are normal (all different)
             }
         }
     }
     int i = 0;
     MeshFilter[] listMeshes = new MeshFilter[meshes.Count];
 
     while(i < (meshes.Count))
     {   
 
         listMeshes[i] = meshes[i];
         Debug.Log(meshes[i].gameObject.transform.position);//the blocks 
  position are all the same (99.0,1.0,89.0)
         Debug.Log(listMeshes[i].gameObject.transform.position);//the blocks 
  position are all the same (99.0,1.0,89.0)
         i++;
     }
 
 
     CombineInstance[] combine = new CombineInstance[listMeshes.Length];
     int w = 0;
     while(w < listMeshes.Length)
     {   
 
         Debug.Log(listMeshes[w].gameObject.transform.position);//the blocks 
  position are all the same (99.0,1.0,89.0)
 
 
 
 
         combine[w].mesh = listMeshes[w].sharedMesh;
 
         combine[w].transform = listMeshes[w].transform.localToWorldMatrix;
         Destroy(listMeshes[w].gameObject);
         w++;
     }
 
     Mesh finalMesh = new Mesh();
     finalMesh.CombineMeshes(combine);
     meshy.GetComponent<MeshFilter>().sharedMesh = finalMesh;
     meshy.SetActive(true);
     #endregion
     Debug.Log("Loaded in " + (Time.realtimeSinceStartup - startTime) + " Seconds.");
 
 }
 }

so my two questions are: How do i get to display the cubes, and why are they all placed at 99.0,1.0,89.0 for no reason ?