Ellen’s address in 1855 was just Enniskillen which makes it hard to know precisely where she was living in the town. Tradition was to marry in the bride’s church. So possibly that’s where she and any siblings were baptised. The following records exist for Trory Church of Ireland:
Trory, St Michael’s (Clogher diocese) Baptisms, 1779, 1784 and 1796-1922; marriages, 1779,
1799, 1801-32 and 1835-1905; burials, 1802-32 and 1835-1915; vestry minutes, 1778-1959.
There’s a copy in PRONI in Belfast. If you are unable to go yourself, you could employ a researcher. Researchers in the PRONI area: http://sgni.net
I notice that one of the witnesses was a William Armstrong. Perhaps Ellen had a brother named William?
I searched Griffiths Valuation c 1862 but there were no Edward Armstrongs listed in Trory or Enniskillen then. That could mean he was dead or it might mean he was lodging with someone and so wasn’t listed.
Death registration started in 1864 so if he died before that you would need to rely on church burial records, where they exist. The only adult Edward Armstrong death 1864 – 1901 registered in Enniskillen was one on 13.4.1866 aged 75. You might want to see if it’s possibly your family. It’s not available to view free. You can view the original certificate on-line on the GRONI website, using the “search registrations” option:
You will need to open an account and buy some credits. It costs £2.50 (sterling) to a view a certificate.
There is a tree on Ancestry (owner Paul Sefton-Stewart) which has Ellen’s father as living 1819 – 1890 and dying in Fermanagh 5th May 1890. That death is of a merchant in Brookborough (not a labourer) and he was too young:
That Edward was probably younger than Ellen and can’t be her father. You could contact Paul and see what his source is but for the moment I would not rely on it as accurate.
Going right back the Armstrongs nearly all originated in the Scottish Borders and moved to Fermanagh between 1610 & 1625. It’s the second most common surname in Fermanagh after Maguire. Elliott is likewise a Scottish Borders surname. They were all known as Border Reivers.