Honestly the biggest thing was differentiating functioning from personal responsibility to fulfill my own needs. Sure I was able to "appear" normal and go to class, work a job, eat 3 meals a day, all that. But I still felt alone with my symptoms and problems because the people in my life meant well but didn't really get it, or some denied/minimized the problem. I was putting requirements on external circumstances and people, only to be let down. Then I was constantly convincing myself I was fragile/broken and also that I (simultaneously) expected therapy and pills and stuff to "fix" me. The pain of acknowledging I had no control over what had happened to me felt too big, and so what I was currently experiencing (intrusive memories, difficulty relating to people, anxiety and anger and other really super fun PTSD stuff) let me say "Well that's it, I'm broken" as a way to not be present or put faith in my own abilities. I'm sure you can guess that it didn't work.
I realized, finally, was that while no one is going to hand me a solution, no one is going to stop me from seeking one either. I don't offer that as an empty platitude, and a couple of years ago I'd be scoffing at this, and finding reasons why I "can't" try. I had to quit therapists who were kind but unhelpful and wait for someone who was more specialized. I had to (with a dr's ok) go off the medication that was allowing me to appear "ok" but just masking the problem without letting me feel enough to actually heal from it, if that makes sense. And it was rough, sometimes I thought I was losing my mind. There's a feeling of "no one understand this but me" and while that can be limiting, the more functional and helpful approach I've found for myself is to say "only I can creatively put together a solution that addresses the nuances of a problem that only I understand."
High functioning to me means figuring out what I need, allowing myself to need it and seeking that fulfillment without putting on external things I can't control. Sometimes this meant admitting that my school performance (I was in college at the time) was compromised and I need to take the quarter off and read some PTSD books and do some intense therapy. Sometimes it meant laying to rest the expectations and disappointments I had in people close to me, and moving on anyway. I think it's all relative to a person's unique situation, but from what I can tell, self-knowledge and care, goal-direction and compassion vs. pity, like you say, are all elements of it.