I sympathize with your feelings! I've been there, and it's hard.
If it makes you feel any better, I have the same prioritization perspective. I actually think there's nothing wrong with it; you realize that "importance" and "urgency" are not simple linear concepts. Everything is important, in different ways!
Anyvay, first off, deep breath: You're not going to get everything done. You may well not move everything forward every week. That's okay. How much are you getting done?
GTD gets all your commitments out and on the table. That can create an overwhelming list, but it's reality! You had all these commitments before; you just didn't see them all at once until now.
I've dealt with this by pruning my Projects list down to things I expect to accomplish--or at least make major progress on--this week. For me, that means a maximum of about 7 Projects. Everything else goes on Someday/Maybe, knowing I may add much of it back on next week.
Does that help?