Hi @CheerBear,
I totally agree with you about the "shoulds." There are shoulds in this world. Children should be safe from sexual abuse. People should refrain from abusing their partners. The basics of life such as food, water and shelter should be available to every human being. There is nothing in the world wrong with "shoulds."
I wonder, does your psychologist believe that clients should call if they need to cancel an appointment??? I would suggest that most do.
But then, what would I know, because apparently my thinking is "too black and white" according to...well...pretty much every person who has ever engaged with me. But you know what @CheerBear? In recent years I've started to think that yes, I AM black and white in my thinking, and I'm ok with that. I believe that post-modern society is simply too grey. I DO believe that there is right and wrong and truth and falsehood and good and evil. It just happens that at this particular moment in history in western society, the trend is to reject these ideas and instead see things as shades of grey. It's simply not cool to talk in absolutes...but that doesn't make it pathological!
I agree with you that your stuckness is because of the stuff that happened. I would imagine that when the stuff is properly processed, you will naturally move past it. Trying to force the moving-past-it stage makes no sense to me. Moving past it will be a natual consequence of processing it. I think perhaps that is maybe a difference between a CBT approach and a more trauma-informed approach. CBT is all about using the front bit of your brain to do things like challenge faulty cognitions, whereas we know from TBKTS that trauma impacts bits of our brain further back. No amount of CBT will change the physiological reactions to trauma. At least, that's my understanding of the argument put forward in TBKTS.
I totally hear you re. the DSM @CheerBear!!! It seems to me that society has done such a good job of pushing the medical model of mental illness, that people really think these diagnoses are actual entities like cancer cells or bacteria. People seem to forget that diagnosing a mental illness is simply a matter of ticking boxes and as you say, a lot of different labels have the same boxes.
What would it mean to you if you did figure out you may have bipolar? My understanding is that the mood swings of bipolar are quite amenable to medication, unlike the big feelings of BPD. One of the reasons BPD is so stigmatized is because medication is so ineffective. Indeed the treatment guidelines say that although you might use medication to treat comorbid anxiety and depression, medication really shouldn't be used to treat BPD per se.
If you actually sit down and read the DSM, it does talk about things like how to do a differential diagnosis between various disorders. I think most mental health professionals miss that bit and that's why people end up with a whole shopping list of diagnoses.
I went through an extremely brief period of being diagnosed with bipolar way back at the start of my muddle. A psychiatrist saw me for five minutes and made the diagnosis. It was ridiculous. Bipolar in no way explains the massive attachment issues that I have. These fit squarely under the BPD label.
For me at this point in my life, my labels of BPD and ASD are important in that they help me understand my muddle and if I ever happen to find a good therapist, they can guide treatment. They also form a core part of my identity. I know people say you shouldn't let a diagnosis define you, but that makes no sense to me. If I didn't have BPD and ASD I would be an entirely different person. I am very proud of the fact that I have made it to forty living with BPD. Thus if someone was to suddenly say I didn't have it, that would invalidate the past twenty year struggle. So yeah, my diagnoses do define me...and I'm ok with that.
Labels are also important when it comes to getting support. For example, I am on the DSP on the basis of having a formal diagnosis. Without the label, I wouldn't have got the DSP. Is that stupid? Yep, but it is the way society works. So to say that labels are unimportant is overly simplistic.
Wow, that all turned into a bit of a rant didn't it. Maybe I need to put a disclaimer in that I'm having my own vent as much as I am responding to your post. 
As to the last point of your post, I have no idea @CheerBear. We are definitely stuck in that particular muddle together. I super badly want to change the world...but could I ever really function in such a dysfunctional system? And do I even want to? I'm super hoping that therapist-take-eleven will be a good match and will be able to help me unmuddle this core part of my muddle.
It certainly is all a giant muddle right now @CheerBear. I wish I had some answers for you, but alas, all I can do is sit here in the mud with you.