So I take it you are searching for her birth certificate?

Did you find her on the 1901 Irish census or Scottish census?
Does it give a place of birth?
Have you found her on the 1911 census? Where does she say she was born?
Was she the first born child? If so, have you checked for her registered under her mother's maiden surname in case she was illegitimate?
Have you checked for variations/misspellings of the surname?
(sorry aghadowey - a couple of 'double up' questions.

)