Use your transaction hash to check on the MEMPOOL if RBF is enabled on the transaction so you can adjust the fees if you want it confirmed faster.
To increase the fee using RBF method, OP has to create a new wallet with importing the private key of the paper wallet.
Now the reason why you weren’t able to use the RBF was because the sending wallet doesn’t have enough bitcoin left to cover up for the fees
This is completely wrong.
OP swept the private key. With sweeping a private key, you create a transaction from the address assosiated with the private key to the existing wallet.
Since the existing wallet doesn't contain the private key of the sending address, there is no way to do RBF and as I said, OP has to create a new wallet using the private key of the paper wallet, if he/she wants to do RBF.