I share your difficulty in creating titles for anything I write. My fiction divides roughly in half this way: either I have a title in my head from the beginning, or else I have nothing that seems to fit. I now understand why so many romance novels have forgettable or annoying titles because I'm having the devil's own time coming up with a title for my own.

Oh, and I'm probably too busy to take it on now, but I'm sure that at some point I'd love to read your HP fic, just as long as your version of Snape isn't irredeemably evil. I can't do Evil!Snape. :-)