I love making string quilts. My size block of choice is 7 inches and I use really thin fabric but any size is ok. It does work nicely to put the same color in the center. I have piles of light and dark strips in bins--doesn't get so wrinkled and just pull from each pile. Sounds like you need some more colors--consider taking fabric from your stash that has been too long on the shelf. A lady that does doll clothes gives me her scraps and the tutti fruitee which I remember as seersucker made lovely blocks. Also the smaller size strips give a zing of color to the block. Do a block or two. My first ones looked so ugly until they were trimmed. I'm sorry you're having a hard time. This is supposed to be fun.