What kind of jack russell is my cheerio?

This is my 6 year old cheerio! We bought her under the impression she was an unknown mix from what we thought was a good place---a few weeks after buying her we saw on the news the kennel had been under private investigation for over 5 years for selling abused/sick dogs and has been shut down--so that is good that they are no longer in business but we have been told by a few vets that she is a pure bred JRT but im still not sure, any ideas?