well they say overeating and eating between meals can encourage gallstones, so it could be that. i'm just always very suspicious of the usual toxins, but clearly our eating/exercising habits have a great deal of influence as well. certainly it has for me. as far as why you are consistently failing to get stones, (assuming you do have them of course) one theory i have is that some big stones could prevent your gallbladder from filling all the way so it would lack the needed pressure to push the big stuck stones out. i needed to study several diagrams of the billiary system before i felt confident troubleshooting. i'm guessing you probably have studied them too. imagine the common duct is backed all the way up past the gallbladder, and/or there is a fat stone lodged in the neck of the gallbladder. or there could be a stone in the gall bladder that acts as a check valve every time the gall bladder contracts, limiting the flow out. or there could be one on the outside of the gallbladder preventing bile from getting in. those little rascals could be doing anything in there!. maybe the stones are just so big and hard they are going to take some time. i believe you are on the right track, have patience!