It's a shame the term is so meaningless that you probably believe it as strongly as someone who believes that you are an SJW (after all, you advocate for transgender people) believes that you are one too.
Be honest: it's a meaningless term, usually applied by anyone who feels uncomfortable about their own racism or sexism (or other prejudices), applied to anyone who made them uncomfortable in any way. If I say "Isn't it a shame the average, well qualified, woman is going to have to fight harder than the average, average qualified, man to get and hold on to a job in IT", it's a simple observation, but I'll get labelled an SJW as a result.
And you? Well, you personally might not. I don't know. You know I'm fairly left wing, and sympathetic to the plight of minorities, but I'm also happy to say when I think people are unfairly demonized, such as Pax Dickinson or the parents of Leelah Alcorn (and to a certain extent you and I had disagreements on the latter, which doesn't surprise me.)
So, given that, what's the point of using the term? Is it used, in practice, for any real life use other than shutting down debate? "OMG! This person suggested I might have certain advantages in life that aren't available to black people, let's call him an SJW and then nobody will take him seriously!"
'cos that's how I see it used. It might, once, by some people, have been used to denote a particular type of over-zealous and highly obnoxious troll who used social justice issues as their weapon, but it doesn't today, and when you use it on Slashdot, you use it in an environment where virtually nobody is referring to those trolls. You're using it in an environment in which it'll be read, and understood, as referring to feminists, civil rights activists, LGB(T*) activists, and, transgender activists, regardless of whether they're hysterical, or just do passive, entirely optional, advocacy, say, in the forms of videos explaining carefully how they feel movies or video games could be improved so that they're not unintentionally a problem for many women.