I got my old wallet file from 2017.
its generated with electrum has no file extension (just a simple wallet file) and when I open it with notepad it contains base64 text.
newer or even older versions of electrum desktop cant read the file.
gives error like: cannot read file

i tried to base64 decode file my self and it contains a json like this:

{
"iv": "a99L8mtf5NlglOvy5gYRzw==",
"v": 1,
"iter": 1000,
"ks": 256,
"ts": 64,
"mode": "ccm",
"adata": "",
"cipher": "aes",
"salt": "li/3f9lSCA4=",
"ct": "Qqw8aL7V3ZWsPjoWSXZ35FieoR/2HelJFQNVXXXX~~~XXXXXdUdsxThBOZ83f5LMrKStykauaTRMvYTA=="
}

I tries to derypt the data with AES mode CCM to find my 12 word seed. (I know my password)
but problem is iv (a99L8mtf5NlglOvy5gYRzw==) is seems wrong!
It looks like base64 encoded and when we decrypt it, its 16 byte! while CCM mode needs 7 to 13 byte nonce.

so this is my python code:

iv = base64.b64decode(data["iv"])
salt = base64.b64decode(data["salt"])
ciphertext = base64.b64decode(data["ct"])
password = b"myPasswordHere"
key = PBKDF2(password, salt, dkLen=32, count=data["iter"])
cipher = AES.new(key, AES.MODE_CCM, iv)
plaintext = cipher.decrypt(ciphertext)
decrypted_text = plaintext.decode('utf-8')
print("result:", decrypted_text)

but its not working and gives me error:
Length of parameter 'nonce' must be in the range 7..13 bytes

my question is what algorithm electrum was using on 2017 to generate the wallet file? is AES CCM correct?
what is my correct 12 byte iv? why its 16 bytes?
any hope to recover my lost wallet?