Erro "No module named django.core.management" ao executar "python manage.py startapp perfis"

Olá!

Realizei a instalação do django==1.7.3 e tenho o python==2.7 em meu computador macOs versão Mojave .

Instalação do django aparentemente OK, mas tomo erro ao executar o "$ python manage.py startapp perfis" a partir do diretório do projeto:

• No module named django.core.management

Log de instalação e erro abaixo:

$ sudo -H pip install django==1.7.3
DEPRECATION: Python 2.7 will reach the end of its life on January 1st, 2020. Please upgrade your Python as Python 2.7 won't be maintained after that date. A future version of pip will drop support for Python 2.7.
Collecting django==1.7.3
  Using cached https://files.pythonhosted.org/packages/4d/b9/b972b87a27330e6647abb9766c1d32e5726430cfcc60b2b9c2f2d0e28bcb/Django-1.7.3-py2.py3-none-any.whl
Installing collected packages: django
Successfully installed django-1.7.3
You are using pip version 19.0.3, however version 19.1.1 is available.
You should consider upgrading via the 'pip install --upgrade pip' command.

$ django-admin startproject connectedin
$ ll
-rwxr-xr-x  1 andrelpg  staff  254 May  7 07:14 manage.py
drwxr-xr-x  6 andrelpg  staff  192 May  7 07:14 connectedin

$ python manage.py migrate
Traceback (most recent call last):
  File "manage.py", line 8, in <module>
    from django.core.management import execute_from_command_line
ImportError: No module named django.core.management

$ python manage.py startapp perfis
Traceback (most recent call last):
  File "manage.py", line 8, in <module>
    from django.core.management import execute_from_command_line
ImportError: No module named django.core.management