I think you may be trying too hard, been there, done that. I always had to ask my sister if I had the right things together. Finally she said, "Do it yourself". That was a good thing. I get a little better each time. Sometimes I just go with whatever the pattern shows. Sign up for the quilting catalogs that we all get in the mail. They have absolutely wonderful color combos. Sometimes I even tear out a page with colors that are beautiful to me. Don't be so hard on yourself. Trust your instinct. Usually the first or second color scheme that you lay out is the one to go with. I squint my eyes to see the lights, mediums, and darks, etc. Just go with it, dive in and have fun. It will fall together, and the light will go on for you soon. Have faith in yourself. You are creative. You just need to let it out and have fun.
"TO HAVE A CREATIVE LIFE, WE MUST LOSE OUR FEAR OF BEING WRONG"