This is a great thread and timely for me. I really do agree with this Countess - ''either this book will succeed and that will mean I am talented and a writer, or it will fail and that will mean I can't write and I might as well give up.'' - I've been feeling like this over the past few weeks since I began to submit my first novel (had three generic rejections so far) - all of this major angst about me being utterly self-deluded about my ability to write and that these rejections mean that I am obviously not able to and thus should give it all up and not bother again. 
It's daft, but I bet most authors think like this from time to time. I'm beginning to appreciate that you need a strong stomach to go forward in this business. I will keep going, because I do feel I have a strong concept, but if nothing comes of this round of submissions I think I may leave it for a few weeks/months, then come back to it for another rewrite, rewrite the submission package etc and have another go, then, if nothing comes of that, perhaps move on (perhaps self-publish, although the thought of all that self-promotion, Twitter etc doesn't fill me with joy) and get on with another. The problem is, the book I've written is the first in a trilogy and I have the plot pinned down in a fairly detailed way for the other two, so I think I should probably get on with the second book - if nothing else, it keeps that writing muscle going.
Whoever said that writing is a vocation - I think there is something in that. I've always had the itch, but it's been particularly strong lately, so there's something in following that up to the best of my ability.
Can I ask about these critique partners / groups - how would you go about finding something like this? Do you have online groups from places like Goodreads/Twitter or do you have local groups? I feel a little on my own with it all and it would be good to have others to bounce ideas off and hopefully who I could help too.
Good luck Shaffron - it does sound frustrating, the woman who took your details but I would agree with Imperial that agents are so incredibly busy that they simply have no time to report back on every submission, much as we would like them to :) Hope you get somewhere soon with yours - maybe a standing back from it all and working on something else would be a good idea at this stage.