I've been scrolling through your work and I must say it's staggeringly good. It's s wonderfully surreal and bizarre, and also very Gilliamesque, which is a style I love. I tried doing this once and it looked pathetic in comparison. Love this stuff!
A rare few of my images are completed as they're originally conceived in my mind's eye. This may sound a tad existential, but I find mental images feel deceiving well finished as they occur to us, but are actually quite opaque. I tend to relay more on improvisation and experiment than preconceived dictates.
Surrealism is the process of allowing our unconscious mind to script creation. Collage art is more the child of that movement than any other. Perhaps your creative process would be eased by dropping your ideas and returning to the medium with a fresh slate.