I am researching the family Devitt / Divitt too - Jane Divitt born in Fermanagh, Ireland in 1785 died in Glasgow, Scotland in 1855 taken from her death certificate. She married William Wark. She came over to Glasgow in 1846. She is my 4th great grandmother. I am thinking that your John Divitt born in 1789 is possibly a brother?
Her fathers name is recorded as John Divitt but her mothers name was unknown.