People if you are close often, as a retailer in a shop lose sight of the big picture and stare at the details. It is easy to do.
Here is a quick report that can instantly show you what people/companies are essential in your business. In register reports go to > stock sales. Now you will find the following report
Click on it. Now although there is a lot of options here, let us make it simple and just put in last financial year
Now, will pop out a report showing which suppliers contributed the most to your business. Often they stand out as it is not uncommon nowadays for two or three suppliers to give you 80% to 90% of your business. I suggest the figures you concentrate are the number of sales and profit. The number will show why people are coming into the store and the profit will tell you where the money is being made.
An interesting exercise here is after studying this report say to yourself "I am a ..... seller"