Вычисление разницы между месяцами и int в django

Я пытаюсь получить разницу месяцев в проекте от даты начала до даты окончания и вычислить ее в ежемесячных обновлениях, чтобы показать процент выполнения проекта, но мой текущий код не дает значения для вычисления. Если я удалю .month, то он говорит о неподдерживаемом типе операнда (типов) для /: 'int' и 'datetime.timedelta'

Models.py

class Projects(models.Model):

id=models.AutoField(primary_key=True)
project_name=models.CharField(max_length=255)
project_manager=models.ForeignKey(CustomUser,on_delete=models.CASCADE, limit_choices_to={'is_project_manager' : True})
client_name=models.ForeignKey(Clients,on_delete=models.CASCADE, null=True)
project_pic=models.ImageField(upload_to='static/website/project-images')
project_start_date=models.DateField(null=True)
project_end_date=models.DateField(null=True)
project_description=models.TextField(null=True)
created_at=models.DateTimeField(auto_now_add=True)
updated_at=models.DateTimeField(auto_now=True)
is_draft = models.BooleanField(default=True)
objects=models.Manager()

class Meta:
    verbose_name_plural = 'Project'

def __str__(self):
    return f'{self.project_name}'



class MonthlyProjectStatus(models.Model):

id=models.AutoField(primary_key=True)
project_name=models.ForeignKey(Projects,on_delete=models.CASCADE)
project_manager=models.ForeignKey(CustomUser,on_delete=models.CASCADE, null=True)
client_name=models.ForeignKey(Clients,on_delete=models.CASCADE, null=True)
attachments=models.FileField(upload_to='static/website/files', null=True)
project_update=models.TextField(null=True)
created_at=models.DateTimeField(auto_now_add=True)
updated_at=models.DateTimeField(auto_now=True)
is_draft = models.BooleanField(default=True)

class Meta: 
    verbose_name_plural = 'Monthly Status'

def __str__(self):
    return f'{self.project_name}'

Views.py

def project_details(request, pk):


projects = Projects.objects.get(id=pk)
employed = Employee.objects.filter(project_site=projects)
invents = Project_Inventory.objects.filter(project_site=projects)
months = MonthlyProjectStatus.objects.filter(project_name=projects).count()

dt = projects.project_start_date.month - projects.project_end_date.month

sums = (months)/(dt) * 100

context = {

    'projects' : projects,
    'employed' : employed,
    'invents' : invents,
    'dt' : dt,
    'months' : months,
    'sums' : sums,

}

template_name ='project-admin/project-details.html'
return render(request, template_name, context) 

d1 = datetime.date(2020,1,1)
d2 = datetime.date(2021,1,1)
dd = d2-d1
days = dd.days  # 366