They're all fine, except that I would also use "í" with "cailín" (though I would more likely just say "seo an cailín..."). (You also mistranslated that sentence in the negative, but I'm assuming that was just an error of distraction)
Also, I would use "an t-oileán" rather than "an inis"; it's a word in more general use to mean "island". "Inis" is a more literary word, mostly just used in placenames these days (you could think of it as something like the difference in English between "island" and "isle"); also "inis" may have slightly different meanings in different dialects.
Good use of emphatic suffixes!