I definitely agree about the sitz bath, peri bottle, depends, maxi pads, bottom balm, nipple cream (I never liked Lansinoh or lanolin ones much there are others I preferred, Dermoplast, Tucks, cold packs, and herb water spritzer. I used all those things.
The items I would add are: prep H cortisone cream in case of hemorrhoids, gel pads for nipples (e.g. Ameda or Medela brands--these feel so good on painful cracked nipples during those first few days), and microwavable hot packs for breasts (Gerber makes some).
Also it is good to have a set of clean comfy nursing bras and pjs handy.
A book is a really nice addition.
Also, if you put some energy bars or candy bars in there you will totally be thanking yourself later. That would have been the one thing I would have added.
Also, print outs of latch diagrams e.g. from Jack Newmans breastfeeding site would be helpful.