You are most likely not allowed to go further because you have what JW's in authority refer to as "BA" or "Bad Attitude".
Shaving your beard will show subjection to the arrangement.
However, as far as the beard preventing you from progressing, that is no longer (as far as I know) a requirement (although in the US you would most likely not be given "special" privileges) and is more or less the personal opinion of your elder body. I spoke with a CO about this several years ago and he insisted there is nothing wrong with it and it is common for elders in Alaska to wear beards.
NO BEARDS was so strongly entrenched in the U.S. congregations that, in my opinion, for the most part it isn't addressed because if they came out and published "brothers can grow beards", there would be a rush to doing it and those who can't grow neat looking facial hair would do it too, then what? Better to let brothers think they can't have a beard then have messy looking brothers.
... nevertheless, it is a religion about control and obedience, find the nearest exit and don't look back again