Is there a django way of grouping records in to groups (groups in a list) and returning a list of ocurrences for each item group?

Question

I have the following list, containing the weeks in the year (python - Django):

weeks = list(range(1,53))

I have a Project model with date_started and date_registered attributes as follows:

class Project(models.Model):
    from_company = models.ForeignKey(Company,on_delete=models.CASCADE)
    project_name = models.CharField("Nombre de Proyecto", max_length=200,unique=True)
    follow_date = models.DateField("Fecha de Seguimiento", default=timezone.now() + timezone.timedelta(days=5))
    date_registered = models.DateTimeField("Fecha de Registro",auto_now_add=True)
    date_started = models.DateTimeField("Fecha de Inicio",null=True)
    last_modified = models.DateTimeField("Ultima Vez Modificado",auto_now=True)

Currently, I'm itterating through each week and get the lenght of the queryset that matches the date_registered__week with the week in the loop, and appending it to a list, like so:

project_active_week = []
for week in weeks:
            if week is not None:
                active_projects = [x.project_name for x in Project.objects.filter(date_registered__week = week,date_registered__year = timezone.now().year)]
                project_active_week.append(len(active_projects))

I have several of this stuff going on and my app has become very slow. Is there a way to perform this more efficiently? Database is Sqlite.

Thank you very much for your help!