DiscoDan, I feel where you are coming from as I had to do plenty of thinking about this same subject, and am still learning as I grow. Hopefully, my point of view can help you in your understanding. Now what I am going to say, I realize may come as a shock to many, not all, but I'm asking you take my point as only that - a point - my own frame of reference. Take from it what you will. Right now it may help you or it may not. I know you will read it with an open mind. Ok, here it goes:
I think you nailed it, with your introduction: "I've been trying to think it through the best I can, and yet I can come up with NOTHING." (my emphasis on nothing)
What I see, is that when you boil everything down (i.e. break apart all the lies), then what you see is that there is NO PURPOSE - IT (life, the universe, existence) just IS the way it is. Why? Because there can be no other way.
Bear with me because I am not trying to rain down on anyone's parade, actually I am trying to do the opposite.
Because as I see it, it is only with this realization that the true beauty of it all "shines" through. How can that be? Well, because once you realize that there is no purpose, there is no meaning, then you realize that EVERYTHING has purpose, ALL has meaning!
I know, I know, it's difficult for me to explain too.
I'll try my best.
How can life be purposeless, yet purposeful at the same time? Well, because it GIVES YOU ALL the POWER! YOU give life meaning, YOU give life purpose. Yes, do whatever it is YOU "want, feel, are inspired" to do. If you want meaning in life create it, if you want purpose in life, then create that too.
What has meaning to you? Well, I can't help you "uncover" that. It is a process you must discover for yourself. Heck, I'm still trying to figure it out for myself!
P.S. I love all the great thinking and ideas that are going around in this forum. It helps me to grow. I just wanted to share my ideas so that it may help you as well.