Magento 2 - Category List Sort by Position with Sub Category Not Working - magento2

Question

A little background, I'm trying to do a custom Category listing, but at the moment it seems the Category not being sort as I seen on Admin.
Here's the code that I've done so far
$current_store = $this->_storeManager->getStore();
$root_category_id = $this->_storeManager->getStore()->getRootCategoryId();
$collection = $this->_categoryCollectionFactory->create()
->addAttributeToSelect('*')
->addAttributeToFilter('is_active', 1)
->setStore($current_store);
return $collection->addAttributeToFilter('entity_id', array('nin' => $root_category_id))
->setOrder('position','ASC');
And the result, when I tried to echo its ID is like below
3
10
4
11
5
7
12
8
15
9
13
14
16
6
But, from the Admin, it doesn't reflect the order correctly, below is the figure
The problem that I realize is, that, I have sub category, I tried to echo the query from above code, and then copy-paste it into sql GUI, and I realize, the position is kinda weird but, it does make-sense, because it's a sub category.
Here's the result when I execute the query on sql GUI
So, what I tried to achieve is to sort above result, to reflecting what I set on Admin.
Is there anything that I missed? I'm not sure where to look, since I've been stuck around 1-2 days, not sure what's the proper keyword, almost all keyword I did will arrive to product sort or kind of that, not category sort
Thanks in Advance!

Answer 1

For those who still needs some answer relating to this question, here's the answer
...
$store_categories = $this->_categoryFactory->create();
$store_categories = $store_categories->load($this->_root_category_id)->getChildrenCategories();
foreach ($store_categories as $category) {
//get id
$category_id = $category->getId();
//get category model
$category = $this->getCategoryModel($category_id);
$sub_children = $this->getActiveChildCategories($category);
if (count($sub_children) > 0) {
$sub_categories = $this->getSubCategory($sub_children);
$categories = array_merge($categories, $sub_categories);
} else {
$categories[] = $category;
}
}
...
The _categoryFactory comes from Magento\Catalog\Model\CategoryFactory.
It's pretty much covering what I want, but not really as I expected before, because I think it's not really efficient.
PS - I'm still new on Magento 2, so, if someone else has other answer that might be pretty much like I expect, then, I'm happily change it as Accepted Answer. :)
Goodluck!