O.K.
So I did everything in the instructions for my android wallet,
and I found some addresses with cash inside.
BUT, the address most funded wasn't found...
In the address book on the app it's marked as an "Old address"
Anybody knows how can I restore this address?
UPDATE:
When I use gurnec's decrypt_bitcoinj_seed, it gives me my seed,
but a warning is popped which says:
1 non-deterministic keys found.
Your mnemonic backup does NOT back up your entire wallet.
I still have the wallet, so how can I back it up entirely?