I am so glad you started this thread as I was thinking it was just me!, its so funny because when I am not dieting and saying 'to hell with it' whatever I eat I don't have any guilty feelings about, but then once you start on a proper healthy eating plan, yes you do have these thoughts that eating something makes you feel guilty, when at one time a whole packet of biscuits in one go wouldn't make me even think twice, its so weird.
When I was at target before and a size 10-12, I used to go shopping for clothes and still be picking up 14's and 16's thinking that I wouldn't be able to get in anything smaller, even though they were too big for me, I'm just starting to be able to get some 12's on again which is a boost but still got a way to go yet