They actually don't look too bad for 7 months old so I am going to guess that at least part of their diet is from free ranging. That will really help a lot. You have actually got the critical stage behind you, that would be when they are growing fast. You will see posts here where folks have a BB turkey around 5 months or so dress out around 35 pounds or more, and some posts where a 5 month old BB can't walk anymore. If you are feeding any grains as a treat, limit any corn that they are getting and encourage them to free range for as long as you can. That not only helps lower the caloric intake, but also encourages them to move around while they are searching for food. I mix some rolled oats in with the feed, it has some protien without the fat. Usually in the winter I do supplement some corn into the diet, but we have some temps in the -30 to -40 range (not including windchill) so they use the extra energy. I have a BBW hen from last spring so she's about a year and a half old and looks about like yours do.
But really, I think your turkeys look pretty good for their age so I would say keep on doing as you have been, just keep an eye on them and limit feed as soon as you see them start having any difficulty getting around (if they even start). And give yourself a pat on the back for the excellent job raising them!
