Dungeon Generator script

Greetings, i have some questions about a dungron generation script im making for a university project. The script is supposed to create a random dungeon but not spawn rooms on top of each other.

This is my script

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 
 public class LevelCreator : MonoBehaviour {
 
     public GameObject startRoom;
 
     public GameObject finalRoom;
 
     public List <GameObject> roomList = new List<GameObject>();
 
     public List<GameObject> levelList = new List<GameObject> ();
 
     // private enum spawnPosition { Front, Back, Left, Right};
 
     public int maxRooms;
 
 
     // Use this for initialization
     void Awake () {
         Instanciator ();
 
     }
 
 
 
     //Adds Randomly rooms to the list and isntanciates them on the level
     void Instanciator(){
 
         for (int i = 0; i < maxRooms; i++) {
             Vector3 spawnOffset = new Vector3 (20,0,0);
             Vector3 nextPosition = new Vector3 ();
 
             if (i == 0) {
                 
                 Vector3 initialPos = new Vector3 (0, 0, 0);
                 GameObject newRoom = Instantiate (startRoom, initialPos, Quaternion.identity);
                 levelList.Add (newRoom);
 
             }  else if (i == maxRooms - 1){
                 nextPosition = levelList [i - 1].GetComponent<Room> ().GetRoomPosition () + spawnOffset;
                 GameObject newRoom = Instantiate(finalRoom, nextPosition, Quaternion.identity);
                 levelList.Add (newRoom);
             }else{
                 nextPosition = levelList [i - 1].GetComponent<Room> ().GetRoomPosition () + spawnOffset;
                 int roomRandom = Random.Range (0, roomList.Count);
                 GameObject newRoom = Instantiate(roomList[roomRandom], nextPosition, Quaternion.identity);
                 levelList.Add (newRoom);
 
             }
         }
     }
 }

The spawnOffset is still not random so the dungeon is still a straight line. how can i check if the room next position is already taken by an object in the levelList?

Thank you