I think I still need to find a Titanite Slab somewhere before I upgrade the Lighting Spear that high. It's supposed to be a great weapon for NG+ too. I should use it more often.
Nope, you're both fucked for this play through, sorry. Still, aside from relighting her bonfire, she's not really all that useful (at least, I've not found her to be so far, I'm past Anor Londo and just backtracked out of the Catacombs). It's a quick jaunt to the Undead Parish bonfire using the elevator shortcut and you can still warp to Firelink without her (but not from, obviously).
Jinsai, what gear do you use?