Oh my goodness, thank you for the replies, and I apologise for worrying anyone.
I was literally musing the point, not asking for support... when you're used to thinking about these things it's easy to forget how much it concerns others. Was actually speaking about this with a friend the other day, that it was nice to speak to each other when we both felt down because other people cannot get past the "Arghh they mentioned suicide! Must fix things!" point of view, and actually it's just really nice and helpful to quietly chat about stuff, and the sort of acceptance of how we both feel. I hope that makes sense. 
Fermats Your comment made me smile, in a gallows humour type of way... It's not a period, it's my life. Admittedly has been worse recently but picked up a bit now.
Actually the professional was generally great - she was concerned about me and understanding, and shocked/trying to explain why so many professionals have been dismissive and misjudged me in the past. The frustrating thing with mental health services is that they are so chronically underfunded that everything is geared towards getting people through a crisis alive, and that's it - there doesn't seem to be any room for the concept that they may not wish to die if they could work on the longterm issues.
Quentin MN led me to finally get a second opinion (well probably a 20th opinion by now..!) and the eventual decision was that ASD was probably lurking there somewhere. And we're back to the "atypical" aka non-male presentation thing again...
WomaninGreen I think most people find it more alarming when discussed rationally - the same may be true for many health professionals. But I've experienced more of the opposite from professionals - like they expect a suicidal person to be obviously emotional, and expect any attempt to be fairly impulsive, so calmy stating how you feel makes them think you are being attention seeking. Adding to this effect is the way that if they do take you seriously, suddenly it's all ambulances and police and A&E... and then nothing. So a huge drama is made and still no actual help at the end of it. Rinse and repeat until you're viewed as a "drama queen".
womanformerlyknownaswoman Oh wow. That could have been written about me. I actually have that book but never finished it, will dig it out. Thank you so much for posting.
TL;DR - mental health services are ridiculous, the women of FWR are awesome, and the bastards are not getting rid of me that easily 