Good luck for tomorrow, I hope it helps. I've just quickly looked your story over and will say that, whilst mine wasn't quite as quick as that, the feeling sounds similar, and I struggled to cope with rapidly accelerating contractions and pain levels with no assistance or reassurance from the midwives. To make it all a hundred times worse, they bunged me in a birthing pool and left me there to drown (as it felt like at the time). When I spoke to the hospital later, they did say that they are aware that fast labours are usually extremely painful and difficult to cope with, and I think we would both agree with that.
It seems very quick after the experience to be talking about it, I found I didn't really start to address birth issues until more than a year later, although I have heard that immediate debriefings can prevent a lot of psychological problems later on.
I made a formal complaint, via a long letter and also a painting that I had done (in counselling sessions) to the hospital and I felt that they handled that very sympathetically. We had a big meeting with their patient liaison officer and head midwife, and the head obstetrician would have been present, excepting that I had not had any obstetric interventions, so it was really a midwifery only issue.
The Birth Trauma Association website I found really helpful, they have a section on making a complaint, and also entered into email support for me. The artwork I did was put into one of their newsletters, it was a bit of a soul-baring moment but is something that down the line I feel strongly about sharing and making more open.
Best of luck with getting your head round everything, and try to enjoy your new baby- 5lbs 8oz is a perfectly respectable weight, dd was 4lbs 15oz just to add to the worries afterwards.