@Fabby, I wholeheartedly agree with what @JennyD said. There are a minority of people who don't fit the gender binary and it's hard enough already for those people to integrate without having pronoun trouble on top of it. Francophone non-binary people are in even more trouble as the language actively works against them. I'm told the same applies to Spanish.
Since English is your fourth language, please allow me to tell you in the spirit of genuine advice that it's basically never okay to use "it" for people.
"It" is totally gender neutral and when used to everyone all the time shows total neutrality on the issue of sex and gender (which I am). Therefore I insist on using "it" on myself and all around me whenever "you" (which is also totally gender-neutral) cannot be used.
Note: this is only in neutral circumstances like this site or the chat room where the gender of a person is unknown and to avoid the use of he/she.
@Celada @casey @JennyD In the mean time I talked to a transgender person I know and she laughed and told me that "IT" is perfectly gender neutral as it's insulting to all sexes and that I should use "(s)he" in English if the gender of a person is not known and the actual "he" or "she" of the gender is known.
"It" is still allowed for inanimate objects, animals or aliens that do not have any gender though...