You seem to have tried everything that my husband tried. I was 19 years old and he was 37 years old when we came into each others' lives(by most unusual circumstances, too). He tried EVERYTHING that you tried, online, casual dating, even church. What worked for him (and me)in the end was simply waiting and not giving up.
He also said that I was not someone who he would have ever imagined dating/marrying. So I suppose that means to have an open mind and heart and plenty of patience to fill the time.