How can I be sure that many to many relationships are created right?

[dseals22]

Hello Everyone,

I have basically 13 different tables. I have Customer table, a Sale table which is connected to Customer table because a customer can buy a Sell and that same Sale table is also connected to an Employee table because an Employee can Sell a Sale. Then I have an Order table connected to a Vendor table because a single order can be placed to a Vendor just as well as many different orders can be placed to many different vendors. But also the Employee table can be connected to a Shop table because an Employee can work at a single shop just as well as many employees work for different shops. The Employee and Shop table is connected by EmployeeShop which have reference or have foreign keys to both the Employee and Shop table. The rest of the relationships can be shown in the pic below. My problem is that I am not entirely sure that some of my tables that are connected to some of the other tables, for example, Ingredient table that is connected to the OrderLineItem, is entirely right. And also Order table and Vendor which are connected by the OrderVendor. Please any help or advice would be beneficial to actually moving on and forward my model to an physical database.