Once more into the breach...

So, grace. Take a step back. Look at the agency. Look at the agent. Think about where your previous three agents failed you. Ask many many questions of this agent to avoid falling into the same and new problems. I know one problem you had was an agent not handling your other genres. Make sure this one is interested in other ideas or already written stories you have. If there were personality clashes of some kind, make sure these won't be the same for this agent (for example, I know an author who makes sure any new agent she gets is willing to communicate all the time and quickly because her first agent disappeared off the face of the planet and never responded to anything she sent her). Talk to current clients to get the positives and negatives of this agent.

Good luck.

That's why you should absolutely talk to current and past clients. Find out their experiences.

And buck up With the quick turnaround you've repeatedly had from losing an agent to getting a new one, your work must be very good indeed. You shouldn't have too much problem with the right agent getting to the next stage (publishing!). Is this your angel novel? I have a soft spot for angel stories and I know how much you love that series.