Django moving from sqlite to postgresql sessions issue

I just attempted to migrate my django (1.9 with python3.4) app from Sqlite3 to Postgresql. Upon migrating ./manage.py makemigrations "app" and ./manage.py migrate and then use loaddata to load back all the users, everything seemed to work find. However when I attempt to authenticate a user with SessionAuthentication I receive the following error:

django.db.utils.IntegrityError: insert or update on table "server_gcssession" violates foreign key constraint "server_gcsses_session_id_6afc9a27_fk_django_session_session_key" DETAIL: Key (session_id)=(b2j6ip8ac29xcvbac7ul3q1wha6mnri0) is not present in table "django_session".

After dissecting the exception, it seems to be that when a user with SessionAuthentication attempts to authenticate via authenticate(username,password) and login(request,usermodel), the Session object is never actually stored in the table django_sessions. The Integrity exception is thrown when I attempt to use the user's session_id as a key into the following model:

class GCSSession(models.Model):
   user = models.ForeignKey(settings.AUTH_USER_MODEL)
   session =models.ForeignKey(Session)

with this query:

GCSSession.objects.get_or_create(
    user=user,
    session_id = request.session.session_key
)

which is triggered with a Django Signal upon user login

I've looked online and the closest thing I found to this problem was this question . However, I'm still not sure what to do, any ideas? Is there a step I missed for migrating?

Update:

This the output of running the above migration commands with sqlite3:

    Migrations for 'server':
  0001_initial.py:
    - Create model ImagingUser
    - Create model GCSSession
    - Create model Picture
    - Create model Target
Operations to perform:
  Apply all migrations: server, auth, contenttypes, admin, sessions
Running migrations:
  Rendering model states... DONE
  Applying sessions.0001_initial... OK
  Applying contenttypes.0001_initial... OK
  Applying contenttypes.0002_remove_content_type_name... OK
  Applying auth.0001_initial... OK
  Applying auth.0002_alter_permission_name_max_length... OK
  Applying auth.0003_alter_user_email_max_length... OK
  Applying auth.0004_alter_user_username_opts... OK
  Applying auth.0005_alter_user_last_login_null... OK
  Applying auth.0006_require_contenttypes_0002... OK
  Applying auth.0007_alter_validators_add_error_messages... OK
  Applying server.0001_initial... OK
  Applying admin.0001_initial... OK
  Applying admin.0002_logentry_remove_auto_add... OK

This is the output of running the same commands with postgresql:

   Migrations for 'server':
  0001_initial.py:
    - Create model ImagingUser
    - Create model GCSSession
    - Create model Picture
    - Create model Target
Operations to perform:
  Apply all migrations: sessions, auth, admin, contenttypes, server
Running migrations:
  No migrations to apply.