To me, they don't look Broad Breasted. Broad Breasted Whites or Bronzes would be wider, I think. Also, if you got them from a local farm, I would think that they would have a breed that could naturally reproduce. BB Whites and BB Bronzes can not breed naturally, so are not great birds for small farmers. It is more likely, in my opinion, that you have a Standard Bronze, and another type of White turkey (White Holland or a mix). I'm not a turkey expert, though, so take my opinion with a grain of salt.
At 3 months old, a heritage bird, even the largest of them, Holland Whites, are pretty light weight wise, while BB Hybrids would be pretty heavy, especially the tom, as they are usually harvested by 6 months old. I hope this helps! Can you weigh them?
To me, they look like broad breasted by the way they are standing. 12 pounds at three months would also suggest BB. Heritage birds walk with one foot almost in front of the other, while BB birds tend to waddle and keep their feet to the sides. If they really are 12 lb, they are BB.