Well I'm not quite sure I do understand.

The way I see it. I have opened the wallet containing the funds. Exported the private keys. Then probably by mistake I have used the sweep private keys (on the exact same wallet which had the funds). I don't think I've created a new wallet nor do I remember having any seed. I assume in order to sweep I was supposed to use the private keys for the current wallet (the one which had the funds right?).

I can't find any wallet file. When you export the private keys, there's a long list of keys. I saw that you can import the wallet using only private key. Does it make any difference if you use all the private keys or only one of them? I can't remember if doing that sweep I have used a specific key or all of them...