Two important things first: trademarks are all about the consumer and they do not technically have to be registered to be valid — so basically if you can prove that consumers recognized your trademark as representing your product before the other company came in, then you may not be forced to change your name. That is just at a very basic level though, of course as with any area of law there are all kinds of technical requirements and legal doctrines to observe.
Another factor that you point out that may be helpful is that you operate in completely different states. Trademarks are limited by geography — so as long as both businesses are operating in non-overlapping markets then there should be no consumer confusion and thus no trademark infringement.
I suggest you speak to a trademark attorney to talk more specifically about your situation and your options. At LawTrades, our trademark attorneys have experience and have helped many others enforce and obtain trademark rights. Visit our website to see what we can do for you.