2) Decide not to antagonize Benjamin during the ghost haunting business
3) Have a water sprinkling conversation with Aoi in front of the gates during Chapter 2?
4) Talk to Aoi about Lucy during the Baby mission, and refuse to date Lucy?
5) Get all previously available Aoi conversations (some of which may require not ignoring the other girls)?
I know you said you're following the walkthrough, but to be honest, I never used it myself, and don't know/remember what all is included, but these are all of the things I can think of that may be important.
Since I remember how much of a pain in the ass it was to fight all the battles over and over again, if you're just plain frustrated at this point and don't want to bother trying to go back and figure everything out, I've uploaded a save at what should be the very beginning of chapter 3 Aoi route, right after the end of chapter 2. I have verified I can get the Aoi spiritual pump conversations from this file (which is what I used to make the basis of my comments the other day), and hopefully you should be able to as well. I can't guarantee that my method of stat raising, or training my characters will be compatible with your playstyle, but it's got to be better than nothing. Sorry I couldn't be of more help. ^^;;