From what I am reading, RAI doesn't treat tall cell very well if at all. Surgery seems to be the treatment of choice. So annual nuclear scans with thyroglobulin levels. I wish there was something more definitive.
Sounds like you have been thorough the ringer. Keep positive and keep fighting. I am going to see Dr. Fagin at Sloan Kettering later this month. Supposedly he is the papillary thryoid cancer "guru". Good Luck!