Description of Problem: I don't have enough space to download Full blockchain, so I added prune=550 dbcache=1000 to bitcoin.conf file.
Do you have private key of the wallet or the address that stores your bitcoin? If you have it, it will be easier for you to pass through the space limit, import that private key to Electrum.
Choose BIP39 when you import it.
However, the sync is taking a long time (11 years).
It is the total time your wallet is behind the latest block on the bitcoin public ledger. It is not the required time to sync your wallet. Depends on your computer capacity as RAM and do you run multi-programs on your computer when you are syncing wallet, the internet connection speed, the total time to sync it will be different. It can be days, weeks or months.
With prune node, you will get troubles to
-- reindex -- to redownload chainstate for your wallet every time it was broken.
Electrum is synced in seconds or minutes.