I struggle with talking about my fics on other sites. I briefly maintained a blog to link to my AO3 posted fics...but I think there was a sense of "who I am doing this for again?" combined with distractability. XD
Sites like Tumblr really are fandom dependent. Certain fandoms have a home there and you can easily find content, but not ALL of them.
I gave up on Twitter while it was still cool! (That is to say, I just did not keep up with it and what it's become has not made returning appealing.)
I honestly feel weird talking about my own works outside of the sites on which they're posted. I become suddenly self-conscious and struggle to go into detail. But, I love hearing about what everyone else is working on and I beta read a lot of my husband's works.