Here's the amount of bitcoin I tried to sent
First transaction (Unconfirmed parent): 0.00051675 BTC
Second transaction(Unconfirmed parent): 0.00047 BTC
Third transaction(Unconfirmed): 0.00021227 BTC
The amount doesn't matter. Take the total fees of all of the transactions and divide by their size. For example:
If TX 1 is paying 1000 satoshis in fees, 300 bytes, TX 2 2000 satoshis in fees, 400 bytes, TX 3 4000 satoshis in fees, 400 bytes. Then the effective TX fees across all of the transactions would be 7000/1100: 6.3 satoshis/byte. If the result of your calculation isn't at least 12 satoshis/byte then you probably won't get a confirmation so soon.