I would suspect that it was 6 inches short by way of mesenteric reach, not bowel length. Hopefully, 1-2cm of rectal cuff will be enough. It definitely is not enough for a double staple technique, but perhaps for a hand sewn anastomosis. Not all surgeons are trained in that procedure, so you will need a surgeon who is experienced with that. You have the right idea of getting opinions of other surgeons. It may be a good idea to do this sooner rather than later, since you'll need to get your reports, imaging films, and labs to the new surgeon.
After waiting a few months, it is possible to use techniques for safely lengthening the mesenteric reach. This is another reason to find a surgeon with special skills. In some cases they use the s-pouch variation, which can add a bit more reach.
Good luck!
Jan