Maybe it's psychological. You're making all these mistakes because you hate the fabric and don't really want to work with it. Only half kidding in that I know I'd be capable of subconsciously doing such things.
Try admitting you don't like it, don't want to do it, but do it anyway. I've read your other posts so know you're disciplined (I'm somewhat like you describe yourself so understand). Perhaps it's just a matter of slowing down, and deliberately plowing ahead until it's done.
Whatever it is, I wish you luck! And show us some pics, why don't you? Maybe we can talk you out of thinking that jelly roll is as ugly as you think it is!