Thanks for the tips everyone! It's helpful to get some ideas from you all.
Meg, I think you're right about heading straight to agency websites and checking out junior agents that way. Good idea!
Richard, I will also try smaller agencies and see how that goes. I'm also a POC writer, and I'm not sure exactly how that's impacted the responses I've received. Hmmm....
Jonny, I can see where you're coming from, but I think I have different reasons for loathing twitter since I'm on the left. At some point, you might want to check out conservative presses and agents. I live in a conservative Christian state in the US, and I've been told that religious presses have the money to publish high quality books. They're not necessarily solely about religious themes either, but all sorts of novels and literature. I don't mean to suggest that this is the right venue for your work. I've just noticed some of your comments on other threads regarding politics, so I thought I'd mention it.