Flutter query random snapshot from firebase

Question

I use firebase firestore to store multiple documents with auto-generated IDs. In my code I generate a random ID and then query the database with "isGreaterThanOrEqualTo: _randomIndex" to read 3 random documents. My issue is: My database is not very big yet. When I use this approach, I sometimes get 0, only 1 or only 2 documents back although I iterate through it 3 times to get 3 documents. I think the reason is because of the limited amount of data there is sometimes no "greaterThanOrEqualTo" ID in my database so I get nothing back.

How can I enhance my code to get always 3 documents back?

My Code:

String getRandomGeneratedId() {
  const int AUTO_ID_LENGTH = 20;
  const String AUTO_ID_ALPHABET = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789';
  
  const int maxRandom = AUTO_ID_ALPHABET.length;
  final Random randomGen = Random();
  
  String id = '';
  for (int i = 0; i < AUTO_ID_LENGTH; i++) {
    id = id + AUTO_ID_ALPHABET[randomGen.nextInt(maxRandom)];
     print('RandomID is $id');
  }
  return id;
  }

  
  
Future<List> getData() async {
    List<Recipe> dataList = [];
    
    CollectionReference myRef = FirebaseFirestore.instance.collection('recipes');
    


    
    // Retrieves 3 random data in a loop
    for (int i = 0; i < 3; i++) {

      // generate a random index based on the list length
      // and use it to retrieve the element
      
      String _randomIndex = getRandomGeneratedId();
       print('RandomIndex is $_randomIndex');
      QuerySnapshot querySnapshot = await myRef
        .where('id', isGreaterThanOrEqualTo: _randomIndex)
        .orderBy('id', descending: false)
        .limit(1)
        .get();
        
        print('QUERYSNAP is $querySnapshot');
       
   
        dataList.addAll(querySnapshot.docs.map((d)=> Recipe.fromJson(d.data() as Map<String, dynamic>)));