I've been querying agents for about a year. I've sent out over 70 queries (one of them to you, I'm pretty sure). While I've had a fair number of requests for partials and three requests for the full manuscript, I still don't have an agent. Maybe my novel's no good. But maybe it is--it's been critically praised by some respected authors and several chapters have been published in literary journals--and there are other reasons for my failure to nab an agent, for example that agents don't think it has enough commercial potential. My thinking has been that if I were to give up on getting an agent I would then star approaching some of the small literary presses and perhaps also enter the novel in the contests through which some university presses select books. So the question: When should I give up on getting an agent? At a year and a half? A hundred queries? How and when do I conclude that my agent quest has failed?
Not "failed" so much as" suspended until we come to our senses and realize what you've got". That happens more than you think.
My benchmark is 100 queries. You may have a problem with your cover letter and first pages if you've only gotten three requests for a manuscript from 70 queries. It's hard to know without seeing the work of course.
I think it's a very good idea to pursue small presses and contests. Agents overlook good stuff more than we like to confess. You catch me on a Friday afternoon when I'm tired and I can overlook a delicate novel as "bloodless" pretty easily. Or if I've seen seven riproaring thrillers in a row, the 8th is probably going to get a pass cause it feels familiar.
You might consider running your synopsis through the crapometer when it comes back from Nicole Richie's launch party.