Mammoth of a Story

So I just barely realized how intense my story is. There's at least one HUGE book before the one I'm working on now, and the one I'm working on now has so much that is involved, that I might end it earlier then originally planned. I think it'll end in an entirely different way then planned...I'm trying to make sure that this one is just reasonably sized. Where I think I'm ending it could be the end of my first book...although it might just be the end of part one of book one (written-wise, not chronologically-wise). I dunno. I'm kinda surprised at where I feel like it should end, but if that's what I still feel is right when I get there, then that's where I'll end it...that would suck though.