Keep looking, something will turn up. Meet as many people as possible and network within networks (sure your doing this).
I have been single for four years now and would love a relationship too, I haven't looked as don't feel quite ready. Still carrying a lot of hurt from the last one.
The times I have met a partner, twice in my life, I remember making significant changes in my life before hand, both involved moving house, to another city. Not saying you have to do that, but the experience of it, a new environment, gave me a fresh start. May be just look at changing thing up a bit, like doing something you haven't done before, doesn't have to be big, could be like joining a book group, or doing a class, recreation group..