create django models from existing sqlite db

I am used in creating orm and leaving django responsible for creating the tables.But in a project I am involved I have to create a simple CRUD application a frontend for an existing database. The database was created by creating the tables manually. So I have two tables Table1 and Table2 which have a many to many relationship through Tables12. Tables12 looks like the table that django would normaly create using a ManyToManyField thus it has two fields the id's of the two models. So after using django's inspectdb, django successfully created the models according to the SQLite database. The many to many tables like Tables12 was created like the following(as stated above):

class Tables12(models.Model):
    table1 = models.ForeignKey(Table1)
    table2 = models.ForeignKey(Table2)

    class Meta:
        managed = False
        db_table = "Tables12"
        unique_together = (("table1_id", "table2_id"),)

Trying the following gives me an error:

>> table2 = Table2.objects.get(pk=1)
>>tables12 = Tables12.objects.filter(table2=table2)
>>tables12
OperationalError: no such column: Tables12.id

I am guessing Django's orm is expecting an id field in every models created. How can I bypass this behavior? Is there a way to edit the tables so as they look more like django's orm but behave as the existing db's tables? Like:

class Table1(models.Model):
    #pre exsiting fields
    table2 = models.ManyToManyField(Table2)

or

class Table2(models.Model):
    #pre existing fields
    table1 = models.ManyToManyField(Table1)

but without destroying database records and without creating tables from start.