I manage this problem by defining myself as being "me" and using mental health definitions - such as disability and personality disorder (which I believe I should be diagnosed as having) - for official purposes.
Yes, exactly this. The world of mental health is so full of grey areas, everyone is an individual. Two people who suffer from effectively the same mental illness may have differing symptoms. Also what tends to happen I think, is many people who have been through the system will come out with more than one diagnosis. Identity crisis!! Personally I've been diagnosed over the years with anxiety, anorexia, EDNOS, borderline personality disorder, aggression and passive aggression, depression and even bipolar disorder (although that was because of the BPD). I see this as basically just a bunch of words to describe all the quirks that make up ME. I am not a bunch of diagnoses, it's all one and the same. Away with the labels ha ha!

And I've also never considered whether the way I am makes me disabled or not, because even though when you're at your worst and you feel completely out of control, the fact of the matter is that you
are in control, you just don't know how to put it to use. It's not like having a physical disability like for example, not having a leg. Sure, any kind of mental illness is debilitating, and I do think that when it comes to some things we need to be easier on ourselves. Particularly when it comes to work/uni/school. If you need time out, take it! When I was at university I ended up having to defer my final recitals and some written pieces of work because of my problems. But I don't think I'm entitled to a disabled parking space. Although..... that would be nice

And as for stigma, it seems to me the best way to fight stigma is to take pride, like all other marginal groups have taken. Not pride in the distress or the illness, but that you have to be a tough person to deal with it every day while having ignorant people being hateful and discriminating against you, and despite this having pride that you can accept yourself for who you are.
Yup yup this too! Sometimes when I'm feeling **** and a bit emo, I think "why did this have to happen to me?" but actually, having come out the other side, it's a good thing. I am definitely a better person for having been through this. Sometimes it takes years and years of suffering, but one day you'll suddenly appreciate something everyone else takes for granted. For me it's things like being able to go out in the sun without wearing a jumper, being able to jog down the road, having a chocolate biscuit, just
feeling in general.
Also, as for depression and anxiety not being taken as seriously, this is probably because they are two of the most common mental illnesses. The NHS is always being pushed in different directions, and in the end what we are, are statistics. It doesn't mean that to
you your problems aren't serious, after all, everyone is affected by and handles things differently. I think in this situation we need to take responsibility for ourselves, cut ourselves some slack, and stop worrying about how we think other people see us (ha ha easier said than done I know). Because what does it really matter whether someone else thinks you're a serious case or not? They're not living your life.