Honestly I was very intrigued (especially as to how you get from the diner to a vampire coven :) ). I'll admit I found the change from third to first person a little weird but that's probably just because I write almost solely in third person.
You're going to watch out for the vampire cliche, obviously, but I like the idea. This is right in the middle of the genre I usually read. :)
Let's see, a few nitpicky things, you wrote, 'letting her eyes wonder,' and I thought you maybe meant 'wander' instead?
'Lillian had been ill since the birth of her youngest child, Sylvia’s brother Marcus, but that had been fourteen years ago, and in that time Lillian would get better before falling ill again, repeated like a vicious cycle.' This sentence doesn't really make since to me. I kind of get what you're saying, but it lacks flow and clarity. I would suggest splitting the sentence, or entirely rewording it.
Maybe something like, "Lillian had been ill since the birth of her youngest child, Slvia's brother Marcus, but that had been fourteen years ago. Since then, though she would get better, Lillian had several relapses until the vicious cycle finally took its toll and ended her life." Or something of the like, obviously with your own spin on it ;)
Hope this was a little helpful and I would encourage you to keep writing!
What is once in a minute, twice in a moment, but never in a thousand years?