I Have been in your shoes. It seemed all my quilts were technically good, seams matched etc. But just lacked some real zip or pizzaz. One year when I attended International quilt show it finally dawned on me why I was just awed by the beautiful quilts. yes they had fabulous designs , but it was the colors. .. I made up my mind no more two or three colors , No more depending on solids to resolve indecition. I dove in , made mistakes but they still looked better than what I had been doing. A few things I learned along the way always have a light, dark and a medium it gives depth. For balance work to add more in each category , light dark and medium. Work on the color wheel , neigboring colors or opposite colors.
One trick is to focus on a season, for me its fall, when I look out and see the range of colors , thats why I like fall. If you like spring think of the beautiful colors at the garden center and why seeing them all in a mass appeals to you. Take the vision and pick your fabrics from them . Color inspiration can come from any where ..a painting ... a jelly roll of fabrics etc. There is a reason jelly rolls are popular .. part of it is the preselection of fabrics we may not have picked. maybe work with one to get you out of your color issue.
To overcome my issue(s), I made a quilt with 19 colors. I went to the store and told myself I only had 1/2 hour to pick, but allowed my self to pick 2 extras , just in case. It worked! I broke out of my issues. I still can get stuck now and again, but I like my final results better.
You can work through the whole color thing! Some LQS will have work shops specifically on this topic.