Technically your answer is wrong. Whilst there's no real difference between the phrase is wanting and wants in English (although if anything "wants" would be more correct in English), there is a slight difference in Gaelic and the phrases are constructed slightly differently. "Is wanting" is a literal translation of this phrase.
I wonder if anyone could help me clarify. Whilst "another" is generally universally used in spoken English (and context clarifies meaning). In written English "another" and "an other" have distinct meanings. viz. "She is wanting another shirt." would be correct where, for example, she currently has four shirts but would wish to have five. But where she has a white shirt but would like this replaced by a blue one it would be more correct to describe the blue one as "an other shirt". French, for example, would distinguish...... where "deux autres bières" would be asking for "two different beers" whereas "deux bières encore" would be asking for "two more beers" I could be wrong but my feeling is that the Gàidhlig phrase is referring to a "different" shirt, that is to say "an other shirt". It would be really helpful if a Gàidhlig speaker would clarify if and how this distinction is made in Gàidhlig.