Google Shopping declined me, GTIN

[Jesse_Brewer1]

Hello, I want to start selling my own t-shirts but when adding products to google merchant account for google shopping they are declining my products. These are not global name brand shirts. They are blanks that I add my own designs to. 
This is the error I get.
 
" Insufficient product identifiers: Missing two out of three attributes [GTIN, brand, mpn] 

When I google t-shirts I see tons of custom made shirts like mine in google shopping from small companies so I know they are getting past the GTIN,MPN issues. Does anyone know what I should do?  

[Jesse_Brewer1]

I forgot to mention the blank t-shirts I use are a name brand, should I use that as the Name Brand and MPN? I just don't want google to think it's a blank t-shirt. for marketing puropses.