Shopping List trouble

When Kenneth started to add new code to the shopping list, I nearly understood all of it, but I may have missed something, but it seems like I have the same code as him?

Whenever I start the application, it runs, but when I add my first item, instead of automatically putting it in the first position, it asks me where I want to put it, messing everything up. Here is the section where I think it went wrong.

Whenever I press enter to add it to the end of the list as well, it adds another version of the item. ex: If I add apples, it will ask what place, or press enter to add it to the end of the list, and if I press enter it adds 2 to the list, so it would look like

1. Apples
2. Apples

def add_to_list(item):
    show_list()
    if len(shopping_list) >= 1:
        position = input("Where should I add {}?\n" 
                         "Press ENTER to add to the end of the list\n"
                         "> ".format(item))
    else:
            position = 0
    try:
        position = abs(int(position))
    except ValueError:
        position = None
    if position is not None:
        shopping_list.insert(position-1, item)
    else:
        shopping_list.append(new_item)

    show_list()