Cytadren is not that bad, as Fonz think. It's not as good as Anastrozole, definately, but in doses no higher then 250mg/day it's very effective and safe. A way better then Nolvadex, at least!
Your body build tolerance to steroids, same way as to other meds, that's why your responce for steroids slowing down.
Also, the further you get from your natural limit, the less "room" for you left to grow...