You can find the right agent for you by finding several books in your genre — and reaching out to those agents.

You have a much higher likelihood of getting an agent who is actively getting books within your genre published.

I would recommend going for smaller literary agents if you’re not currently signed. It’s a lot harder to get the ‘big dogs’ to notice you if you aren’t already a successful published author.

Make Sure You’re Giving Agents What They Want
When you submit to agents, what exactly are you sending over? You referenced that you’re sending your entire book to literary agents. Most agents don’t have time to read a novel in its entirety, so it’s standard practice to send only a few chapters of your book, a 1-2 page synopsis, and a query letter. One of the main reasons you may be having trouble getting your book published is that you’re not following the typical procedure. Most literary agents are picky with this type of thing (trust me, I know from experience). Be sure to follow the typical procedure so you look more like a professional author with experience!