This might be due to OP checking up the bitcoin balance in other blockchains like BCH. Either way, there is no other go to check the wallet balance other than importing private keys in bitaddress.org. So OP should have pasted his private key in bitaddress and verified the balance and would have posted the address alone in blockchain and could have verified it in other non-btc blockchains.
How bitaddress.org shows wallet balance? I can't find this feature on bitaddress I tried to import a dummy private key on "wallet details" but it only shows QR code, Public key and private key compress and uncompressed.
So, where do you think you can check the balance of your wallet through bitaddress?
And honestly, it's not safe to import the private key to online generators like bitaddress while you are connected to the internet.