Create flask-sqlalchemy database is failing

Im trying to import my app config (db_config.py) via:

>>> from app.db_config import db_session

Error received 'ImportError: No module named 'app.db_config'; 'app' is not a package

app.py looks like:

import pymysql.cursors
from flask import Flask, render_template, request
from flask_migrate import Migrate
from app.db_config import db_session

#app setup
app = Flask(__name__)
app.config['DEBUG'] = True
app.config['SQLALCHEMY_DATABASE_URI'] = 'mysql://root:mypass@localhost/mydb'
db = SQLAlchemy(app)
migrate = Migrate(app, db)
@app.teardown_appcontext
def shutdown_session(exception=None):
    db_session.remove()

@app.route('/', methods=('GET', 'POST'))
def index():
    return 'meow'
if __name__ == '__main__':
    app.run()

db_config.py:

from sqlalchemy import create_engine
from sqlalchemy.orm import scoped_session, sessionmaker
from sqlalchemy.ext.declarative import declarative_base

engine = create_engine('mysql+pymysql://root:mypass@localhost/mydb',
                                         convert_unicode=True)
db_session = scoped_session(sessionmaker(autocommit=False,
                                         autoflush=False,
                                         bind=engine))
Base = declarative_base()
Base.query = db_session.query_property()

def init_db():
    import app.db_table
    Base.metadata.create_all(bind=engine)

db_table.py:

from sqlalchemy import Column, Integer, String, DateTime, Boolean
from sqlalchemy.ext.declarative import declarative_base
from app.db_config import Base

Base = declarative_base()

class Tld(Base):
    __tablename__ = 'Tld'
    id = Column(Integer, primary_key=True)
    uri =  Column(String(80), unique=True)
    tmstmp = Column(DateTime())
    auth = Column(Boolean())

    def __init__(self, uri=None):
        self.uri = uri
        self.tmstmp = tmstmp
        self.auth = auth

What am I doing wrong here? I'm following this tutorial but Im not receiving the output i expected.

Is something wrong with my app.py that makes it not callable like that? or something else wrong with it?

(First time alchemy user)

Thank you so much