Smoking and weight
Hi Kerry and welcome to the 3FC website. I don't know much about fibro but I'll bet there are plenty here that do. Have you looked further down the list of groups to see if there is any fibromyalgia stuff down there. Could be under Dieting with Medical conditions Thread.
The following is some information I found in our local Sunday paper lift out called Body and Soul. It listed 12 common mistakes people make when trying to lose weight. This is one of them. You may not be able to increase the activity level that much as it seems like you are already working out, but have a read and see if this might fit the bill.
12. smoking instead of eating
Despite the huge health benefits of quitting, many smokers worry about gaining weight when they stop. Some studies have shown that smoking cigarettes increases metabolic rate and recent non-smokers do report an increase in appetite once they quit, but the health risks outweigh the perceived benefits. When you quit, increase your activity level to burn off extra kilojoules and tackle the need for oral satisfaction by chewing on fruit or raw veges when you feel a craving coming on.