Fletcher Ancestors

I am looking for information on my Fletcher ancestors. I have an obituary for my 3 great grandfather, Alfred Fletcher born between 1836-1838 in "Queens County Ireland". I have his father's name as Thomas Fletcher and his mother as Dorah Jordan. His mother arrived  in New York on the Ship Lorena out of Dublin on 15 Sept 1851. She arrived without her husband Thomas Fletcher.  He was not listed on the passenger list.  She did arrive with 4 children. Alfred age 15, Dorah age 11, Emma age 9 and Sydney age 7.

Dorah Jordan Fletcher was born about 1801-1805. Thomas Fletcher was born about 1813. I am wondering if Thomas died and Dorah brought her family to America. I would love to find evidence of the marriage of Dorah Jordan and  Thomas Fletcher. I do not know their religion, but there is no evidence of any Catholics in our family in America.

Any birth or baptism records of their children would also be good clues.

I am still looking for Thomas in America, and trying to trace Dorah also. Alfred ended up in Michigan and then Iowa.

Thank you for any help.

Deborah Huse