I am agent hunting

at present. No, we are not going to sell the house. I am looking for an agent for a book I have written.
I have written other books. They languish in "the bottom drawer" of my computer files. There are a number of reasons for this. I will not go into them here except to say that some of them may yet get dusted off and looked at. It will all depend on whether I get an agent.
Last year one major publishing company asked for synopses by e-mail. I hesitated and then sent mine but heard nothing.
This year a much smaller but reputable company here in Australia asking for synopses and the first three chapters. I duly revised the synopsis to their specifications and sent it and the first three chapters away. They returned them recently saying it was not for them but with the suggestion that I should try elsewhere.
I was not surprised that the book was not for them. It has been a long time since they published a serious middle grade book. These days they go for the lightweight, shorter book. Do not mistake me. The writing is good but the books are aimed at restless readers.
In the meantime I had been thinking about agents. It is, I believe, almost as hard to get a reputable agent as it is to get published. At the same time most reputable publishing companies will not look at unsolicited manuscripts. I have researched this matter in depth. I understand the reasons for it.
The most successful agents often say they are not taking on any new clients. This is undoubtedly due to the fact that they wish to do the best they can for their current authors. I understand that too and I would not wish them to do less than their best.
So, where does it leave me? I am slowly and cautiously making approaches to possible agents. I am trying to find out what sort of people they are and who their clients are. It is sometimes surprisingly difficult. Sometimes I look at lists of authors and I do not know their work. Their books are not in our local library. How can I tell what the agent likes if I cannot read the author's work.
A bad agent may be worse than no agent at all. A bad publishing deal may be worse than no publishing deal at all. I keep reminding myself that.
One agent has just got back to me. The book is not for her but my story has merits. She also suggests I try elsewhere. I do not know what to read into this. Is my writing not quite good enough or is really just not something she wants to handle? Should I really try elsewhere? Perhaps. It is difficult.
I have submitted to just one other agent at the present time. I am preparing to try a third. I have been told I should dive bomb all agents at the same time. I have also been told I should tread slowly and carefully and try at most two agents at a time.
This whole business puzzles me and frustrates me. I do not know what to think apart from one thing.
I wish there was an agent for agents!