John Gormley, County Tyrone to USA, 1849

I'm researching my ggg-grandfather John Gormley, born in Ireland about 1831. When he became a US citizen in Medway, Massachusetts, USA, in 1854, he said he was from County Tyrone in the paperwork. He married Bridget Sheridan in Medway in 1855. His marriage record states his parents were Owen and Mary Gormley. Bridget's parents' names were not stated.

I believe an 18-year-old Irish farmer, John Gormly, who arrived in Boston from Liverpool on the ship Living Age in May 1849 was the same person. Furthermore, there was a 16-year-old Bridget Sheridan on the same ship who very well could have been the woman he married 6 years later (and could have been from County Tyrone as well).They were Catholic; will that narrow down the number of parishes they could have been from?

I'm new here and still learning my way around; I hope you'll be tolerant.