Your gains have slowed. Thats a clear indication you need to stop.
Its not possible to gain continuesly for 6 months. The body grows in short bursts.
Get off now. Run HCG at 1000ius/ED for 14 days, with Arimidex 0.5mg/ED.
Then conduct PCT with Clomid/Tamox. Or better Toremifene.