Most definitely YANBU!! I felt traumatised by the birth of DS1, only I didn't realise/acknowledge it at the time. I just thought this must be how it is, pull yourself together. I was physically and emotionally traumatised by it - it was a relatively long labour 24hrs, various complications incl it being discovered fairly late on he was deflexed OP (basically back to back with head extended rather than chin to chest - about the worst position!), blood loss etc. Ended up having him in theatre with forceps (my community midwife later read my notes and commented that she was amazed it hadn't ended in a C section. I suffered from terrible piles afterwards and was very sore with that and stitches for episiotomy.
It was only after I'd had DC2 that I realised how traumatised I'd been, because by comparison it was a breeze and I just felt ok afterwards. Sore of course and tired, but not traumatised. It was a much more straightforward and quicker labour, which helps of course. Plus it wasn't my first time, so I knew what to expect etc.
It just made me realise how hard it had been first time and how I should have sought help and support at the time to enable me to come to terms with what had happened. I know that when the "baby blues" kicked in on day 5 after DC1, all I kept dwelling on as I sobbed into my pillow was the birth itself and how I felt I'd let my baby down.
Now I know that you can request a debrief with the hospital/birth centre, and someone will take you through your notes and talk about what happened and hopefully help you to fill in any blanks or better understand why certain things happened/were done. I'd definitely recommend this based on how you are feeling. It is entirely normal to feel how you are, as I've discovered from talking to lots of mums since, but it isn't something you have to just accept and live with.
I am certain in hindsight that I suffered from PND to some extent after DC1, and would attribute it to the birth and my reaction to it. Please don't suffer and isolate yourself, approach your midwife or the hospital and see if you can go back and talk it all through.
I do hope you start to feel better soon.