I know what you mean about the complexity of the forms, and trying to get them committed to memory, and then trying to get them "just right." Hyungs are, by far, my favorite part of TSD, so that combined with my perfectionist-by-nature personality makes me put myself through the wringer a whole bunch, too! I remember when I first learned Pyung Ahn Ee Dan I felt exactly as you do about the higher level forms -- they seem so involved, so long, so demanding, and so complicated. And to a certain extent, they are! But I'm sure you'll be able to learn them -- you are capable of far more than you're giving yourself credit for. Just be patient.
What I've seen, time and again, is that I tend to follow a few stages in learning each new form. First I have to get it in my head -- know the sequence, know all of the individual techniques in proper order so that you can "dictate" them to myself as I work out and train.
Then I have to learn to perform the movements correctly -- this can be fairly tricky, especially if the form incorporates some new techniques that I haven't really done previously (like your kick-punch-side block in Ee Dan, for example -- for me, one of the first biggies was learning the scoop and turn movement that follows the first spear hand in Pyang Ahn Sam Dan -- for some reason, that one really threw me!).
Then, once I've got all of the movements "working," it takes time to get it "nice." Get the pacing solid. Make each technique distinct but also find a rhythm that makes the transitions and combinations of techniques that are embedded in the form work "better." Tweak hand position, foot position, hip position, get the stances lower, and so on and so on and so on. As I've progressed, I've found this is the stage where I spend most of my time. This is especially true of the Chil Sung forms for me -- relaxation and grace doesn't come naturally to me, so Chil Sung forms tend to present some very particular challenges! Chil Sung Ill Rho took me a solid 3 months to get to a place where I felt it was good enough to present at tournament. And I'm currently at 4 months working on Chil Sung Sam Rho and I'm still not entirely thrilled with it -- just hope I don't embarrass myself at Nationals!