so it's all because of that 1 trnsaction without a fee (was an accident) that the others don't confirm too?
0.01 mbtc works perfectly all the time with my previous few 1000 transactions
some time is still today?
Since the wallet send the change back to the same address in the same transaction which is unconfirmed, transactions after that will not be confirmed unless the transaction which the change is in confirms since those transaction spends the change coins. If you choose to spend a output which is confirmed, the transaction will get confirmed in the next block if transaction fees is high enough.
If you include a 0.01mbtc transaction fees in a transaction and it gets confirmed quickly, it may be because of your coins having high coin age or a pool which mined that block having a policy of accepting transactions which have low transaction fees.