Django 3 error: No installed apps with label 'app_name'

I am currently learning how to use Django 3 (and Python 3.8) and I am following a tutorial to create a simple blog. I am getting a good grasp of the basic concepts so far but I am stuck at creating a migrations file.

When I enter the python manage.py makemigrations blog command into Windows Powershell, I get the error message: No installed app with label 'blog'. I have searched high and lo for an answer but I am still scratching my head. I am wondering if you lovely people would be able to offer any advice on the matter.

Here's my settings.py file:

import os

# Build paths inside the project like this: os.path.join(BASE_DIR, ...)
BASE_DIR = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))
print("BASE_DIR = ", BASE_DIR)

# Quick-start development settings - unsuitable for production
# See https://docs.djangoproject.com/en/3.0/howto/deployment/checklist/



# SECURITY WARNING: don't run with debug turned on in production!
DEBUG = False

ALLOWED_HOSTS = []


# Application definition

INSTALLED_APPS = [
    'django.contrib.admin',
    'django.contrib.auth',
    'django.contrib.contenttypes',
    'django.contrib.sessions',
    'django.contrib.messages',
    'django.contrib.staticfiles',
    'blog',

]

MIDDLEWARE = [
    'django.middleware.security.SecurityMiddleware',
    'django.contrib.sessions.middleware.SessionMiddleware',
    'django.middleware.common.CommonMiddleware',
    'django.middleware.csrf.CsrfViewMiddleware',
    'django.contrib.auth.middleware.AuthenticationMiddleware',
    'django.contrib.messages.middleware.MessageMiddleware',
    'django.middleware.clickjacking.XFrameOptionsMiddleware',
]

ROOT_URLCONF = 'django_project.urls'

TEMPLATES = [
    {
        'BACKEND': 'django.template.backends.django.DjangoTemplates',
        'DIRS': [
            os.path.join(BASE_DIR, 'templates'),
        ],
        'APP_DIRS': True,
        'OPTIONS': {
            'context_processors': [
                'django.template.context_processors.debug',
                'django.template.context_processors.request',
                'django.contrib.auth.context_processors.auth',
                'django.contrib.messages.context_processors.messages',
            ],
        },
    },
]

WSGI_APPLICATION = 'django_project.wsgi.application'


# Database
# https://docs.djangoproject.com/en/3.0/ref/settings/#databases

DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.sqlite3',
        'NAME': os.path.join(BASE_DIR, 'db.sqlite3'),
    }
}


# Password validation
# https://docs.djangoproject.com/en/3.0/ref/settings/#auth-password-validators

AUTH_PASSWORD_VALIDATORS = [
    {
        'NAME': 'django.contrib.auth.password_validation.UserAttributeSimilarityValidator',
    },
    {
        'NAME': 'django.contrib.auth.password_validation.MinimumLengthValidator',
    },
    {
        'NAME': 'django.contrib.auth.password_validation.CommonPasswordValidator',
    },
    {
        'NAME': 'django.contrib.auth.password_validation.NumericPasswordValidator',
    },
]


# Internationalization
# https://docs.djangoproject.com/en/3.0/topics/i18n/

LANGUAGE_CODE = 'en-us'

TIME_ZONE = 'UTC'

USE_I18N = True

USE_L10N = True

USE_TZ = True


# Static files (CSS, JavaScript, Images)
# https://docs.djangoproject.com/en/3.0/howto/static-files/

STATIC_URL = '/static/'

And here's my models.pyfile of the blog app:

from django.db import models

class Author(models.Model):
    name = models.CharField(max_length=100, unique=True)
    email = models.EmailField(unique=True)
    active = models.BooleanField(default=False)
    created_on = models.DateTimeField()
    last_logged_in = models.DateTimeFieldP()


class Category(models.Model):
    name = model.CharField(max_length=100, unique=True)
    slug = models.SlugField(max_length=100, unique=True
    author = models.ForeignKey(Author, on_delete=models.CASCADE)


class Tag(model.Model):
    name = models.CharField(max_length=100, unique=True)
    slug = models.SlugField(max_length=100, unique=True)
    author = models.ForeignKey(Author, on_delete=models.CASCADE)


class Post(models.Model):
    title = models.CharField(max_length=200)
    slug = models.SlugField(unique=True)
    content = models.TextField()
    pub_date = models.DateTimeField(auto_now_add=True)
    author = models.ForeignKey(Author, on_delete=models.CASCADE)
    category = models.ForeignKey(Category, on_delete=models.CASCADE)
    tags = models.ManyToManyField(Tag)

I'll also post the directory to my blog app as well:

first_project
  --my_venv
  --django_project
    ----django_project
      ----__init__.py
      ----asgi.py
      ----settings.py
      ----urls.py
      ----wsgi.py

    ----blog
      ----migrations
        ----__init__.py
      ----templates
      ----__init__.py
      ----admin.py
      ----apps.py
      ----models.py
      ----tests.py
      ----urls.py
      ----views.py
    ----templates
    ----manage.py
    ----db.sqlite3

EDIT: Sorry about the missing blog app files, I've added the auto-generated files to the directory.

I'll also add the apps.py file, which is:

from django.apps import AppConfig


class BlogConfig(AppConfig):
    name = 'blog'

As requested, this is the result of the command python manage.py showmigrations:

admin
 [X] 0001_initial
 [X] 0002_logentry_remove_auto_add
 [X] 0003_logentry_add_action_flag_choices
auth
 [X] 0001_initial
 [X] 0002_alter_permission_name_max_length
 [X] 0003_alter_user_email_max_length
 [X] 0004_alter_user_username_opts
 [X] 0005_alter_user_last_login_null
 [X] 0006_require_contenttypes_0002
 [X] 0007_alter_validators_add_error_messages
 [X] 0008_alter_user_username_max_length
 [X] 0009_alter_user_last_name_max_length
 [X] 0010_alter_group_name_max_length
 [X] 0011_update_proxy_permissions
contenttypes
 [X] 0001_initial
 [X] 0002_remove_content_type_name
sessions
 [X] 0001_initial