Next time you try free motion quilting, try using an ope toe free motion foot rather than a darning foot. Not knowing the machine that you are using makes it difficult to recommend a particular foot, but most darning feet have a very small circular hole making it difficult to see. An open toe free motion foot will make it much easier to see where you have been, where you are currently stitching and where you need to go.
Just an idea, but see if this works for you.