Thanks for your long thoughtful post math, sorry its taken so long to reply.
I don't know what to say to the crisis team when they ask what I want them to do. I don't know what the actual available options are, for a start. And if I call them it's because I've exhausted all other options and am no longer able to think of something to help, it just seems like another expectation I can't meet. Although when things were happening when I was younger I could have done with being hospitalised for a bit, that wouldn't help now (and I'd never get admitted anyway). TBH I don't think they can do anything, not now. I only call because I'm aware that's what I'm supposed to do.
Thanks for explaining the suicide thing from their POV... but it seems like a weird paradox. Because if I've definitely made up my mind to kill myself, I'm not going to call them then, am I? As it is, I rarely call them because it's just so difficult. There doesn't seem to be any way of sort of pre-empting it, of making things better so that I don't feel/think it's a good idea any more. Their model of suicide only captures the "sudden crisis" type, where something provokes suicidal feelings and there's a narrow window of opportunity to intervene. It doesn't capture the gritting-your-teeth-and-trying-to-go-on-everyday-and-eventually-drowning-in-it type. (Gosh, after typing that I think I've realised why I get so many nightmares about impending disaster that I'm trying to prevent but no-one will help).
There aren't any trauma services in my area... as it is it's only the ASD diagnosis that has meant I might be able to access therapy, most people can only access the IAPT services (who don't accept you if it's considered "too complex").
They are operating with the hope of beginning as they hope to proceed
Let's just be clear here - I asked them for help almost eight years ago (this time around - also tried when younger). I had a CPN briefly who got involved in sorting out benefits, then left without explanation. Told to keep waiting as was on list for therapy. 18 months (ish) later - find out no longer on waiting list. Have tried periodically ever since to get back on it, but service has changed/been cut (?). Everything has to go through CMHT, who have assessed me several times and decided no therapy each time, unwilling to explain why in a way that actually makes sense, lots of buck-passing, excuse-making, can never get to the bottom of things. GP has kept re-referring me to them even though they always write back saying please don't refer her again, we can't do anything. Their antics make me feel sick and hopeless. The utter powerlessness of it, it feels like an abusive relatioship where I'm hanging on because I need something only they can provide, but it's destroying me. That is really bizarre, because this dynamic in any other situation and I'd have LTB! Can never find out anything or do anything about it, because everyone just says "go and see your GP". No-one seems to be able to comprehend the concept of the CMHT rejecting the GPs referral. I have spoken to people at the PALS, and they seem to get it, until they "make some calls to find out what's going on" and then get back to me, and, as if hypnotised, parrot "Go and see your GP..." Even contacted MPs office at one point, they seemed very helpful, until I received a letter from them a few days later telling me to make an appointment with my GP who would refer me to the CMHT... 
(btw I have gone to see my GP and get referred every time.)
A couple of people have attempted to advocate for me, but they are immediately steamrolled, unused to the workings and diversion tactics of MH services. One friend attended an appointment with me and came away in shock at the manipulation. Another called them, concerned about me, and they said not to worry they'd get my care-coordinator to call. Except I didn't/don't have a care-coordinator...
So, whilst I am open and honest with them, and have taken each new appointment as a fresh start, forgive me if I'm a little sceptical and not seeing them as my saviours. They are definitely not "starting" as they mean to go on - hopefully they are finally realising they've made a mistake and going to do something though.
...with you working on actively discerning and choosing what you need from the mental health services that are available, engaging with what is offered, and ultimately becoming your own best advocate.
The mental health services available so far have been... nothing. I have "engaged" with appointments, assessments etc, and had my hopes dashed many times. This is what's so weird about all this, that people dont seem to understand - I've done bloody well at figuring things out, working out what helps and what doesn't, trying to do as much positive stuff as possible, and frankly just remaining alive this long. I've not been in a downward-spiral of self-destruction or anything (apart from a brief period aged 17). I knew the past was affecting me and went to services explicity to try to get therapy to deal with it. But I haven't been able to, so whilst in many ways I am a hell of a lot "better" than I was 8 years ago, in anther way I am quietly falling apart, losing any scrap of hope, and closer to suicide than ever. It feels much more ... rational. Not a sudden reaction to something happening, but a quiet "can't do this anymore". Too much time passed, too much pain acquired, too many opportunities lost.
Sorry to be depressing, it's just this aspect is one of the hardest things about it all. The way everyone seems to have a narrative about how things should work, and can't/won't countenance anything else. So eg. most of the world says "MH services that way" but MH services shut the door in your face. Or people who do know about services are like "this is what you should do" because that's their experience, but it doesn't match yours. The worst thing about this is that small scraps of support that would help are witheld unless you fit the supporter's internal idea of what is happening (MH professionals and ordinary people). I think that's why I'm so petrified of getting anything "wrong" - because people, especially MH professionals, seem to be searching for something they can say "oh well you should be doing/thinking xyz" so they don't have to engage. Obviously this is impossible when their advice contradicts itself or fails to take reality into account.
Re. trauma - there's not a specific thing. There sort of was, but not something that would be considered traumatic enough for an official diagnosis of PTSD. But it's the way that had an effect on me, that led to more situations that I couldn't handle, and have trauma symptms from, but again nothing on it's own counts as "trauma". It's the comunded effect it's had on my life - a ghastly example of one thing leading to another without timely intervention and never the right environment for long enough to heal. There's sort of two strands... one, getting horrible memories and stuff, and the other is just being exhausted from swimming agaonst the tide trying to keep going, to make progress but too little too late, and grief for all that is lost, and hopelessness for all that will not happen.
Sorry.