I've been taking the digestive bitters for almost a year now and I've taken lecithin off and on for at least that long as well.
Try being more consistent with the lecithin, and make sure to use the granules, not the liquid. Also make sure you are getting plenty of fiber in your diet since this also helps with bile formation.
Does stress play any part in the formation of gallstones/sludge? Cause I've dealt with plenty of stress this last year!!!
Stress would have very little effect. Hormones are one of the biggest factors for women. Bile levels are the other really important factor. This is where the bitters, lecithin granules and fiber come in.
I know the gut is VERY sensitive to stress/mood, etc. Hopefully I haven't screwed up my guts beyond repair!