I think it would be easier if you had the master public key, either xpub, ypub, or zpub, of your wallet. Just try this one below to show all addresses with balances.

- https://www.blockchain.com/explorer/assets/btc/xpub/<your-xpub/zpub-goes-here>

If it doesn't work, try this one: https://blockpath.com/ just paste your master public key if it shows used and addresses with balances; collect them and import it as a watch-only wallet to Electrum if it's not more than 1,000 addresses.
After you imported these addresses, you can see the total balance.