Unity3D: How to save an array of gameobjects with arrays of position in xml and load them back in correctly?

Hello everyone! I don´t know how this question system works. I am relativly new to unity and even newer to serialization and deserialization. I just picked it up 3 days ago. Now I am stuck. Here is a complete rundown of the game part that needs to be saved. I created a game, where the player starts on an instantiated field of objects. The player can then built new objects by left-clicking and destroy objects by right-clicking. Because this is a map creator it´s a good idea to be able to save the map. So i had to get a save system. I had to realise quickly, that there are no tutorials that fit my needs. So i only had 2 options: either give up or try to create my own saving system. I did the second one. And it works!. . . kind of. Not really. Basicly i got four classes: 1 that stores the data, that is going to be serialized, 1 that contains all the data, that is going to be transferred to the first class, 1 that just contains the amount of objects and 1 that gives every object an ID. Right now i only store the Vector3 position as 3 floats, the IDs of the gameobjects and the number of gameobjects (you are going to see everything in this question). When pressing M the Save function gets called, when L is pressed, the Load function is called.

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//Class 1: This is the one contains the data, that is saved and loaded

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[System.Serializable]

public class XMLSerialize {

 public float[] PosX;
 public float[] PosY;
 public float[] PosZ;
 public int[] BlockID;
 public int AmountOfBlocks;

}

//Class 2: This one just contains the amount of blocks and might be a little overkill.

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public class AmounOfBlocks : MonoBehaviour {

 public int AmountOfBlocks;

}

//Class 3: This one is responible for getting the custom ID of every Block in the scene. It sits on every object, that need to be saved.

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public class GetInstanceId : MonoBehaviour {

 public AmounOfBlocks amounOfBlocks;

 public GameObject thisObject;
 public int elementId;
 void Start()
 {
     thisObject = this.gameObject;
     amounOfBlocks = AmounOfBlocks.FindObjectOfType<AmounOfBlocks>();
     amounOfBlocks.AmountOfBlocks++;
     elementId = amounOfBlocks.AmountOfBlocks;                
 }

}

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Class 4: This is the big one: it is responsible for Saving, Loading and converting the data to and from XMLserialize

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[System.Serializable]

public class XMLManager : MonoBehaviour {

 public XMLSerialize xmlSerialize;
 public AmounOfBlocks AOB;
 public GetInstanceId[] getInstance;
 public static XMLManager xmlManager;

 public int AmountOfBlocks;
 public int[] InsatnceID;
 public float[] PosX;
 public float[] PosY;
 public float[] PosZ;
 public GameObject[] reprGameObject;

 public bool saving = false;

 
 void Awake()
 {
     xmlManager = this;
 }
 public void Update()
 {
     
     AOB = AmounOfBlocks.FindObjectOfType<AmounOfBlocks>();
     getInstance = GetInstanceId.FindObjectsOfType<GetInstanceId>();

     AmountOfBlocks = AOB.AmountOfBlocks;

     PosX = new float[AmountOfBlocks];
     PosY = new float[AmountOfBlocks];
     PosZ = new float[AmountOfBlocks];

     xmlSerialize.PosX = new float[AmountOfBlocks];
     xmlSerialize.PosY = new float[AmountOfBlocks];
     xmlSerialize.PosZ = new float[AmountOfBlocks];
     xmlSerialize.BlockID = new int[AmountOfBlocks];


     reprGameObject = new GameObject[AmountOfBlocks];
     InsatnceID = new int[AmountOfBlocks];
     for (int i = 0; i < AmountOfBlocks; i++)
     {
             InsatnceID[getInstance[i].elementId - 1] = getInstance[i].elementId;                                
             reprGameObject[getInstance[i].elementId - 1] = getInstance[i].thisObject;

              xmlSerialize.AmountOfBlocks = AmountOfBlocks;

         if (reprGameObject[getInstance[i].elementId - 1] != null)
         {
             PosX[getInstance[i].elementId - 1] = reprGameObject[getInstance[i].elementId - 1].transform.position.x;
             PosY[getInstance[i].elementId - 1] = reprGameObject[getInstance[i].elementId - 1].transform.position.y;
             PosZ[getInstance[i].elementId - 1] = reprGameObject[getInstance[i].elementId - 1].transform.position.z;

             if (saving == true)
             {
                 xmlSerialize.PosX[getInstance[i].elementId - 1] = PosX[getInstance[i].elementId - 1];
                 xmlSerialize.PosY[getInstance[i].elementId - 1] = PosY[getInstance[i].elementId - 1];
                 xmlSerialize.PosZ[getInstance[i].elementId - 1] = PosZ[getInstance[i].elementId - 1];
                 xmlSerialize.BlockID[getInstance[i].elementId - 1] = InsatnceID[getInstance[i].elementId - 1];
             }
         }
     }
     if (Input.GetKeyDown(KeyCode.M))
     {
         SaveData();
     }
     if (Input.GetKeyDown(KeyCode.L))
     {
         LoadData();
         for(int i = 0; i < xmlSerialize.AmountOfBlocks; i++)
         {
             PosX[getInstance[i].elementId - 1] = xmlSerialize.PosX[getInstance[i].elementId - 1];
             PosY[getInstance[i].elementId - 1] = xmlSerialize.PosY[getInstance[i].elementId - 1];
             PosZ[getInstance[i].elementId - 1] = xmlSerialize.PosZ[getInstance[i].elementId - 1];
             InsatnceID[getInstance[i].elementId - 1] = xmlSerialize.BlockID[getInstance[i].elementId - 1];

             Instantiate(reprGameObject[InsatnceID[i]], new Vector3(PosX[getInstance[i].elementId - 1], PosY[getInstance[i].elementId - 1], PosZ[getInstance[i].elementId - 1]), Quaternion.identity); 

         }
         saving = false;
     }
 }
 
 public void SaveData()
 {
     XmlSerializer serializer = new XmlSerializer(typeof(XMLSerialize));
     FileStream stream = new FileStream(Application.dataPath + "/Saves/levelsave.xml", FileMode.Create);
     serializer.Serialize(stream, xmlSerialize);
     stream.Close();
     saving = true;
 }
 public void LoadData()
 {
     if (File.Exists(Application.dataPath + "/Saves/levelsave.xml"))
     {
         XmlSerializer serializer = new XmlSerializer(typeof(XMLSerialize));
         FileStream stream = new FileStream(Application.dataPath + "/Saves/levelsave.xml", FileMode.Open);
         xmlSerialize = serializer.Deserialize(stream) as XMLSerialize;
         stream.Close();
         
     }
 }

}

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There are a couple of problems in my code, none of them are compiler errors, as you can see. But i might have goofed somewhere with the arrays. I just can´t detect the problem. Whenever the player destroys a block of the original platform, the index of the array is too large. Whenever i load in the save, the index of the array is to large. Sorry if my english isn´t the greatest and the formatting of this question is terrible, but it´s the first time i wrote a question on this forum. I am really bad at explaining my problem, so if anything is mispelled or unclear, feel free to ask me. Thanks in advance.