Julie, I don't think I've ever heard of anyone stalling from using nicotine gum. Sorbitol is a sugar alcohol and some people metabolize them better than others. According to this link each piece of Nicorette gum has 3 calories and less than 1 gram of carb. If it were me, I'd count each piece as 1 gram of carb.
That said, the makers of Nicorette do not recommend that anyone use their product for longer than 12 weeks, so you are probably wise in wanting to stop at this point.