flask_sqlalchemy module cant be found error

So I want to use the flask_sqlalchemy module in my web app. But when I run "flask run" it gives me the following error:

        from flask_sqlalchemy import 
        SQLAlchemy
        ModuleNotFoundError: No module 
        named 'flask_sqlalchemy'

I am running this in a virtual env with python3.7 and pip3. It says that all packages have been installed. Ive tried a whole bunch of things with no luck.