My company creates and distributes "custom newsletters" but the closest category I was offered was "Publisher" which may be true in a broad sense, but that's not a word someone would search on. How do I add "Custom Newsletter Service" to the options?
Re: Product/Business Category
Don't worry. This is the category you filled for Google, which they will offer related suggestion and algorithm for you instead of nothing.
To simply put. you just need to put what people would probably search in your keywords and that's what only matters for your business.
Good luck on that!