While offline I pondered the personal information the medium supposedly divined. I'm guessing that you have a land-line phone or cell phone with a calling plan. That means your number will come up on caller ID. Your area code gives them at least the state you called from and the whole number gives the medium your name, your husband's name, and your address. From that information a simple web search can provide a wealth of other personal information unless you have made a determined effort to not give out information including avoiding contests, verifying with every company that they don't sell/share your info, and other efforts some might consider paranoid.
The only way for you to verify to yourself that the medium didn't Google you and then feed your info back to you to deceive you is for you to Google yourself and do your best to find out what is available about you and your husband online. Be aware, there are information companies that scour the web to gather data then sell access to it. The medium could subscribe to such a service so a cursory online search for your own info might not be thorough enough. For you to be sure the medium is genuine you really need to make a diligent effort when Googling yourself.