the translation seems good, but it would be better to use the prep. НО insted of И, because it's necessary to convey the idea of contrast implied by BOTH in English,
This р word always has a negative connotation.
I think сдержанный is a very good choice to translate 'demure'. In Russian it means reserved in a positive way (in expression of one's feelings and emotions). But it is used regardless of the gender.