Many of my bottles extract batches seem to become over carbonated after a month or so in bottles. I use the correct amount of priming sugar for the style I am brewing based on a priming calculator online. Many of my batches do not hit the intended FG, they usually finish 3-4 points higher than the recipes call for, even when I raise the fermentation temp, roust the fermenter, etc they still finish a bit high. I have read that extract will typically not hit the expected FG. My question: is it possible that some unfermented sugars left over after primary fermentation are getting fermented with the priming sugar and creating more carbonation? is there a formula to use to add in the suspected unfermented sugar when calculating priming sugar prior to bottling? Would using a different priming option (I use priming sugar) help eliminate this from happening, if it is indeed my issue?