There are LOTS of Ellen McDonnells going to America from Queenstown around that same age. Here are a few...
30 Sept.1904 "Baltic" arrived New York
Ellen Mcdonnell, age 18, from Swinford, going to cousin Annie Durken in Philadelphia- entry has been crossed out which means she did not sail on this voyage
19 Mar.1905 "Cymric" arrived Boston
Ellen McDonnell, age 20, travelling with Mary Heally- both names crossed out
8 Apr.1905 "Cedric" arrived New York
Ellen J. McDonnell, age 20
3 Oct.1912 "Cymric" arrived Boston
Ellen McDonnell, male!, aged 24, born Claremorris, mother Mrs M McDonnell Kilbride Claremorris Co Mayo, going to cousin Thomas Morris at 89 Gardiner St Newtown Mass, had been in Newtown previously (6 years)