How to know if your domain is trademarked

Hi all!

I know the obvious answer to the above question is to type in your domain name into USPTO Trademark Search System and see the results, but what if the search results give you some similar but not exact wordings?

For example, I bought "LuminaStyle.com". When I searched the trademarks engine, there are some results that had "Lumina" registered companies but if "Lumina" is genuinely trademarked, how come these companies are not suing one another for using their name?

I understand based on preliminary research that if a company uses a trademarked word but operates in a different business sector, they still might be able to use it but what is the yardstick to use when purchased a domain is a no-no?

Thanks in advance!