Add orders to a cart (multi-page form)

Hi there, I am creating a logistic app whereby This User (users who login) will enter orders for multiple customers. I am having issues adding things to the cart correctly. I’d appreciate any help from anyone who has worked on a shopping cart before.

My data structure is as follows with some columns omitted for simplicity:
Unique ID (default from Bubble)
Product Name

Unique ID (PK default from Bubble)
Customer Name

Unique ID (default from Bubble)
Orders (FK)
Product (FK)

Steps to create a new order is as follow:

  1. Fill in the customer information
  2. Add things to the cart.

Step 1

Step 2
The icon + and - is to add and remove items from the cart

I ran into an issue that when I clicked + for the first time, it’s adding 2 items to the cart instead of 1.

My workflow when the + button clicked is like this:
(1) If the cart does not have data with order-id as passed from the URL AND does not have the product-id = the current cell, then create a new Cart row.

(2) If Cart already has a row with order-id as shown in the URL AND product-id = the current cell, then update row by adding 1 to the Qty