How does our perception of ourselves change?

[APeacefulWarrior]

This makes sense. I guess my worry is concerning losing who I perceive myself to be right now.

Nothing of value is ever lost.  However, it can change.  And change is a constant, at least in 3D land.  Who you are right now is not who you were yesterday or who you will be tomorrow.  Each experience you have changes you, whether by a little or a lot.  It's as inexorable as the movements of sand on a beach, as wind and water continually pushes it about.

And for me, at least, much of the joy of living is specifically in understanding my self as fluid, and so getting to continually discover who I've become, day by day. I think I'd get quite bored if I ever thought of myself as a static, unchanging thing!

I know this is an emotional response, but I can't help it. I don't want to go to sleep again, having to wake myself back up in another life. It just seems tragic, and painful.

Well, if you're from a higher density, you don't have to do it over again.  Or, at least, if you wanted to incarnate again you could do it someplace a lot less stressful than here on Earth.  

But just the same, higher-you chose to do this, and clearly there's something you want to learn from this life - so much so that you decided to take on the pain of incarnation behind the veil, on one of the most confused planets in the galaxy, in the middle of one of its most tumultuous eras.  Perhaps if you meditated on your reasons for incarnating, you'd get a better idea of what you were hoping to get out of life.  

Understand your purpose, and you'll understand a lot more about why you're here and why you're you.