Problem while reading document from firestrore in flutter

I am new to Firebase I want to read all data of document here is how i am trying to read

This is my function to get data.

Future<List<AgencyModel>> getAgencyData() async {
   List<AgencyModel> agencyListModel = [];
    try {
      agencyListModel =  await _db.collection('colelctionName')
        .doc('myDoc')
        .snapshots()
        .map((doc)=> AgencyModel.fromJson(doc.data()!)).toList();
        print('List : ${agencyListModel.length}');
      return agencyListModel;
    } catch (e) {
      debugPrint('Exception : $e');
      rethrow;
    }
  }

This is how i am calling the above function

getAgencyDetails()  async {
   List<AgencyModel> data = await  fireStoreService.getAgencyData();
    print('Data : ${data.first}');}

and this is my models class fromjson function

 factory AgencyModel.fromJson(Map<String, dynamic> json) {
  return AgencyModel(
    agencyName: json['agencyName'],
    agencyContact: json['agencyContact'],
    agencyAddress: json['agencyAddress'],
    cnic: json['cnic'],
    agencyContactDetails: json['agencyContactDetails'],
    certificatesUrl: json['certificatesUrl'],
    locationUrl: json['locationUrl'],
    earning: json['earning'],
    processing: json['processing'],
    onHold: json['onHold']);}

I am not getting any error or exception, Also these two print statements does not work not display anything not even the Strings List : and Data : i.e

print('List : ${agencyListModel.length}');
print('Data : ${data.first}');}