That is a really good book (if triggering for many trauma survivors due to being...rather explicit in specific examples of traumas similar to many readers! D: ). That said, I believe that it really was the seminal one that basically changed a lot of the applied complex trauma field that I see today. IIRC he's been responsible for trying to get cPTSD into the DSM for like... 30 years at this point? Legend. There's even a ton of hit pieces on him on Google when searching for trauma memories/false memories, I'm assuming from the fact that he was court witness over how trauma memories can be extremely accurate due to how the PTSD overspill works. People who have money, no morals, and are in the group that would do things to their children that no one should do... I don't have proof but that is quite interesting. Especially as many articles (even one that got published on the NIH website in connection to him negatively) have surprisingly little substance and such.
Anywho.
Don't rush the process please, of whatever it is. Your body and brain are probably right in some way. It's okay to practice breathing and what Pete Walker talks about in his book, or my go-to starter for anyone even near the topic -- Janina Fisher's "Healing the Fragmented Selves of Trauma Survivors". So good, very little triggering too which is excellente by me.
The main book people read on Polyvagal therapy that's really popular and well rated us good too, I think the author may have been a Susan? That's a good follow-up but more a rider-on/adjunct to me of a very specific "okay how do we get the body in a more continuous kind of safe state. :D :)"