Titling my work

Alright, so it's not exactly completed yet but I'd say it's a decent enough way into the story that I should have some basic idea of what I want it to be called. That's the problem. I don't. I have no idea in fact and it's driving me a little insane as I sit and think on it. It's difficult to be original in the case of something that should be quite brief a hook and somehow still capture the essence of the story.

I also have a continuation on from this so it should be something that can flow into other stories, or at least have a base brand name with a subtitle of some sort, or maybe I'm really just over thinking it and should just leave it untitled. I don't want to settle on a title I'm really attached to just to have it tossed out the window by an editor.

Is there a method? Will it just eventually jump out at me as I'm writing?  I've been throwing around a few ideas, trying to glance at others series and how they've gone about it. Twilight (though it really annoying me to keep referring back to this) picked a particular theme and stayed with it. I saw one yesterday that had gone with similar sounding/spelled words as their titles. Delirium, Pandemonium, Requiem etc. Picking one work and alternating what follows Beautiful Creatures, Beautiful Darkness, Beautiful Chaos and so on.

Then there's the iconic character.... Harry Potter and _______ any title to follow.

Since my character goes through a bit of a name change that simple wouldn't work. I want something that has a hook, that is attention catching that can be thrown around in conversation without confusion. I want to tap into the history of the novel, the legacy these characters are faced to live up to, not only from their parents but for the main character especially hundreds of years of ancestry before her.

I had been thinking of The Legacy.  Then I had thought of The Legacy of Ard Rí (a-rd rig) which literally means High King (which ties into the historical aspect but seems to pass over the fact that the characters despite their status are modern day teens). An additional issue, here poses the pronunciation problem and the fact that I can't picture that flowing into multiple continuations which, i currently have in my head.
Uniformity, is what I'm looking for within the story itself and the stories to follow. I know I should just finish writing the manuscript and let it go, just hoping that something will present itself. Or let some people read it and offer suggestions, maybe have a brain storming session. The fight continues.