Category or Single Title

I got my first rejection Saturday.It was a bummer, to be sure. I gave myself over to a brief "mourning" period, had a good cry and then really looked at the letter. I submitted to Harlequin, thinking that I was writing a category romance. Unfortunately, my story doesn't fit into the parameters of this line. Some part of me knew this all along. As I scrolled through the submission guidelines for each line, I thought, "You know, none of my stories fit into any of these lines." But, hey, I gave it the 'ol college try anyway.I've discovered that my writing is a lot like my personality: I just can't seem to fit a round peg into a square hole. I was reading the last issue in RWR and I was struck by the author's statement, "When a door shuts, find a window" (I'm paraphrasing here).So, I'm finding my window.Because I can tell you right now that my second WIP is definitely not going to "fit" into any of the category parameters either. My window, such as it is, is single title. I'm standing on the edge of a precipice, fear pummeling my heart, self-doubt whispering "I don't know, Jen, are you sure you can do this?" For some strange reason, I'm terrified to make my book longer. I know I need to just bite the bullet. Get back on the proverbial horse and get my butt in gear. Beside, I can't know unless I try, right?I think I made the mistake of thinking that category books were easier to write. This, I have discovered, was a gross miscalculation on my part, not to mention a big load of crapola. I think categories are, in fact, harder to write. But, why can't I let go?