I think you're mixing keys and addresses here. Let me clear this:
You swept the private key into another wallet
The new wallet isn't showing your BCH/BTG balance, just your BTC.
You think that your coins are lost due to sweeping.
Is that correct?
Moving a private key to a new wallet doesn't influence the balance and it can't remove "its capacity". Your coins are probably still there. Could you post one of the addresses that held BTC at the time of the forks?
FIXED
Great. Where did the problem lie? My guess would be that you were checking the balances on a BTC chain.