We never see her like that in-game, but it's mentioned on the Eidolon Wall that she used to look like a child but now appears as a woman. There's also some artwork of IX's Shiva as a fairy that I forgot to add (and will now do so), which ties into the Eidolon Wall mentioning that in some places, Shiva appears as a fairy due to the Eidolons adapting their forms to the cultures in which they appear.
EDIT: Wait, that artwork isn't from this Ultimania, so I won't be adding it after all.
Those different lines are as follows (translation by hitoshura) –
Cloud: “Let’s go home, Tifa.”
Cloud: “There’s also something we’ve got to do when we get back.”
Cloud: “We haven’t seen what’s beyond that mountain yet.”
Tifa: “Right… let’s go back.”