I'm not sure about this, but it seems like there are two different impulses going on here,
@digger, but you should tell me if I'm wrong.
The first is around being worried you may have or act on suicidal thoughts. You said you won't because of your son, but you worry that your reason is not enough. I understand that. You seem quite stable right now. Of course there's no guarantee that won't shift.
The second is around meaning in your life, a reason to get up in the morning and care about your life.
I think these are related but ultimately different concerns. I think suicidal thoughts and actions are temporary, even for those who actively struggle with them. They come and go. Unless of course the ultimate decision is made when the suicidal feelings are present, and that's their danger. It doesn't sound like you're struggling with suicidal thoughts right now though. That's what I meant when I said you've made a contract with life to stay. Maybe that could change, but right now in this moment you've done everything you can to ensure that you're not suicidal.
I think a sense of meaning would give you another reason besides your son not to kill yourself, but it would do so much more too. In the hierarchy of concerns, not killing yourself is basic but finding a sense of meaning is higher level. This is something that I'd guess most people we know struggle with, whether or not they have trauma backgrounds. Someone mentioned Victor Frankel's "Man's Search for Meaning". I was surprised when I read that book that Victor Frankel relates the human search for meaning to the modern era, one that coincides with a shift towards secularism. People used to know what the meaning of life was: their religion told them. According to the existential psychologists, including Victor Frankel, life for moderns is pretty bleak as we turn away from God. That book is quite religious, by contemporary standards.
You asked me how I got to the point where "life is fine, I'm fine with it." I think that just means that I'm stable. After lots of work, I don't have to deal with PTSD symptoms most days of my life, and my health is usually okay. Even when things are bad, when I feel badly, I have the presence of mind to know my feelings will change. Yet, that statement doesn't contain joy in it. I enjoy life a lot sometimes. I'm fond of riding bikes, the natural world, good food to eat, animals, some special friends. Do I feel that my life specifically has higher meaning though? Or, that I ought to be alive for some larger purpose? Not really, no. No.