I can sympathize a little, most people 20-30 are getting married, or not interested in marriage, they aren't online dating. Try being divorced and under 30...
I sometimes wonder if I'm doing myself a disservice by not considering men who are younger than me?... perhaps I'm not the only one, and that's one of the reasons you are having trouble meeting people? I have a whole lot of life experience in 28 years. So my profile may say 28 but my soul and my heart are like 40! lol :) So I'm not sure I would have much in common with someone under 30.
I'd encourage you to just keep reaching out to people you find interesting. You never know :)
You want a topic? How about young adult groups that are made of mostly 19-21 yo's? lol. I was fun when I was 20 and thought I was all grown up, but who was I kidding? And I don't want to hang out with a bunch of 20yos now that I'm almost 30 :)