Native American English speaker and university student here (primarily NE US).
It indeed is and has been the literary standard for a long time to default to the masculine pronoun when the subject gender is ambiguous or unknown, although using
they as a singular gender-neutral pronoun is not unheard of (indeed, there are contexts where
they as the singular is preferable). This english.SE thread is a good discussion of this subject. In professional contexts, these are the only pronouns you need concern yourself with.
In recent years however, social justice movements and the rise of concepts such as cis-gender privilege have created subcultures (primarily amongst adolescents to university-aged students) where using pronouns such as
she is indeed offensive (the consequence of the notion that "gender" is something that you identify as, rather than your biological sex). In fact, some universities, even reputable ones such as Wesleyan, have adopted the use of gender-neutral pronouns. (In personal experience, the most commonly recognized are the Spivak,
xe pronoun sets). Such pronouns, however, are nowhere near commonplace and are not ever expected to be.
Moreover, within the LGBT community itself (and even that acronym is under fire; certain communities will insist on LGBTQIA and others will add even more letters), there is no particularly universal consensus on acceptable pronouns. Dan Savage, a noted columnist of the community, describes here one particularly illustrative experience speaking to such an audience at UChicago.
In short, there do exist 21st-century gender-neutral pronouns and even pronouns for genders that are not the traditional male and feminine genders. These pronouns, however, are highly uncommon, almost never encountered in serious professional or academic context, and largely limited to LGBT subcultures obsessed with being politically correct. There are very few English speakers who will even recognize pronouns such as
xe, even fewer who will care about it, next to none who will call you out on it, and as a foreign speaker, you'll most commonly be received as someone who's mispronouncing the standard pronouns (